GLUE,  GELATINE,  ANIMAL  CHARCOAL, 

PHOSPHORUS,  CEMENTS,  PASTES, 

AND  MUCILAGES, 

COMPRISING 

THE   RAW   MATERIALS  AND   MANUFACTURE   OF  SKIN   AND  BONE   GLUE, 

DIFFERENT  VARIETIES  OF  GLUE,  ANIMAL  CHARCOAL,  PHOSPHORUS, 

GELATINE  AND  PRODUCTS  PREPARED  FROM  IT  ;  ISINGLASS  AND 

FISH-GLUE,  METHODS  OF  TESTING  GLUE  AND  GELATINE, 

AND   THE    PREPARATION    AND   APPLICATION   OF 

CEMENTS,  PASTES  AND  MUCILAGES  FOR  USE 

IN  THE  WORKSHOP,  LABORATORY, 

AND   OFFICE. 


BY 

F.  DAWIDOWSKY, 


EDITED  FROM  THE  GERMAN,  WITH  EXTENSIVE  ADDITIONS,  INCLUDING 
A  DESCRIPTION  OF  THE  MOST  RECENT  PROCESSES. 

BY 

WILLIAM  T.  BRANNT, 

EDITOR  OP  "THE  TECHNO-CHEMICAL  RECEIPT  BOOK." 

ILLUSTRATED    BY    FIFTY-NINE    ENGRAVINGS. 

SECOND  EDITION,  REVISED  AND  LARGELY  RE-  WRITTEN. 


OF 


Av 

T  •  \ 


PHILADELPHIA: 

HENRY  CAREY  BAIRD  &  CO., 

INDUSTRIAL  PUBLISHERS,  BOOKSELLERS  AND  IMPORTERS, 

810  WALNUT  STREET. 

1905. 


COPYRIGHT,  BY 

HENKY  CAREY  BA1KD  &  CO. 
1905. 


PRINTED   BY  THE 

WICKERSHAM  PRINTING  CO., 

53  and  55  North  Queen  Street, 

LANCASTER,  PA.,  U.  S.  A. 


PREFACE  TO  THE  SECOND  EDITION. 


THE  first  edition  of  this  work  has  been  out  of  print  for 
some  years,  but  nevertheless  there  is  a  constant  demand  for 
it,  and  this  together  with  the  fact  that  frequent  inquiries 
are  received  for  information  in  this  department  of  industry, 
are  the  inducements  which  have  led  to  the  preparation  of 
the  present  treatise. 

The  book  is  arranged  in  two  parts,  Part  I.  comprising 
Glue,  Gelatine  and  Allied  Products,  and  Part  II.  Cements, 
Pastes  and  Mucilages,  and  it  is  fully  illustrated  with  en- 
gravings of  various  types  of  apparatus. 

Since  the  appearance  of  the  first  edition  much  progress 
has  been  made  in  the  manufacture  of  glue  and  allied  pro- 
ducts. Old  and  wasteful  methods  of  working  have  been 
replaced  by  more  approved  processes,  and  in  the  present 
volume  it  has  been  endeavored  to  place  before  those  inter- 
ested in  these  industries,  a  practical  and  comprehensive 
account  of  modern  methods  of  operation. 

In  order  adequately  to  represent  this  advancement  and 
development,  the  best  authorities  have  been  freely  consulted 
and  drawn  upon,  special  acknowledgments  being  due  to 
the  following  works :  "  Bone  Products  and  Manures,"  by 
Thomas  Lambert,  and  "  Glue  and  Glue  Testing,"  by 
Samuel  Rideal. 

As  the  demand  for  phosphorus  is  steadily  increasing,  and 
the  manufacture  of  this  product  from  bones  and  bone-ash 
forms  an  important  branch  of  the  utilization  of  bones,  it  has 
been  deemed  advisable  to  devote  a  chapter  to  this  subject. 

The  receipts  for  cements,  pastes,  and  mucilages  given  in 

(in) 

1413 


IV  PREFACE    TO    THE    SECOND    EDITION. 

Part  II.  have  been  gathered  from  numerous  sources.  They 
have  been  critically  examined,  and  are  offered,  with  the 
full  conviction,  that  they  will  not  be  found  wanting  in 
efficacy. 

The  Table  of  Contents  and  Index  have  both  been  care- 
fully prepared,  and  being  very  full,  will  make  reference  to 
any  subject  in  the  volume  easy  and  satisfactory. 

W.  T.  B. 
PHILADELPHIA,  PA.,  AUGUST  10,  1905. 


CONTENTS. 


PART  I. 

GLUE  AND  GELATINE. 
CHAPTER  I. 

NATURE   OF   GLUE. 

PAGE 

Sources  of  glue;  Change  in  the  animal  tissues  by  continued  boiling;  Defi- 
nition of  what  is  known  as  glue;  Most  important  glue-yielding  sub- 
stances ............  1 

Transformations  of  which  glue  and  gelatine  are  the  products;  Transition 
stages  of  glue;  Production  of  the  glue-yielding  substance  of  the  animal 
body 2 

Crude  glue  and  jelly;  Constitution  of  glue;  Combinations  of  which  glue 
consists  ............  3 

Preparation  of  pure  glutin;  Properties  of  glutin        .....       4 

Preparation  and  properties  of  chondrin     .......       5 

Adhesive  power  of  glutin  and  of  chondrin;  Properties  of  glue  and  its  be- 
havior towards  other  substances;  Quantity  of  glutin  in  glue  .  .  6 

Properties  of  jelly  before  drying  to  glue;  Absorption  of  ozone  by  the 
jelly;  Behavior  of  glue  solution  towards  different  salts;  Effect  of  acids 
upon  glue;  Meta-gelatin  .........  7 

Combinations  of  tannin  with  the  jelly;  Effects  of  dry  heat  upon  glue; 
Chemical  composition  of  glue  and  glue-yielding  substance  ...  8 

CHAPTER  II. 

USES   OF   GLUE. 

Glue  as  a  joining  medium,  and  requirements  for  this  purpose  .         .         .10 

Glue  as  a  binding  agent;  Consumption  of  glue  in  the  manufacture  of 
matches  .  .  .  .  .  .  .  .  .  .  .11 

Quality  of  glue  required  by  book-binders;  Glue  in  sizing;  Glue  for  cul- 
inary and  medicinal  purposes  .  .  .  .  .  .  .  .12 

Glue  for  clarifying  and  fining  beer,  wine  and  other  liquids;  Bouillon 
tablets;  Glue  as  a  healing  agent 13 

(v) 


VI  CONTENTS. 

PAGE 

Glue  for  elastic  masses  and  a  partial  substitute  for  rubber;  Use  of  glue  in 

photolithography;  Hectograph  mass;  Glue  for  fancy  articles         .         .14 
Gelatine  veneers  and  their  uses 15 

CHAPTEK  III. 

RAW  MATERIALS  AND  THEIR  PREPARATION  FOR  THE  MANUFACTURE  OF  GLUE. 

Principal  substances  employed  for  the  manufacture  of  glue;  Division  of 
raw  materials  into  groups      .........     16 

Animal  skin  and  its  constitution        ........     17 

Portion  of  the  skin  of  value  for  the  manufacture  of  leather  and  glue; 
Yield  of  glue  from  tannery  waste;  Influence  of  the  age  of  the  animals 
from  which  the  skins  have  been  derived  upon  the  quality  of  the  glue   .     18 
Notes  in  reference  to  judging  glue-stock  .  .-  .         .19 

Liming  of  waste       .          .         .         .         .         .         ...         .         .20 

Precaution  and  care  required  when  buying  glue  leather;  Arrangements 
required  for  the  preparation  of  glue  stock;  Location  of  the  glue  factory; 
Lime  pits;  Contrivances  for  washing  the  limed  stock    .         .         .         .21 

Washing  drums;  Pits   or   vats  with    proper   arrangements  for   stirring, 
draining    and    inspection;     Glue   stock   washer   invented   by   W.    A. 
Hoeveler,  described  and  illustrated       .......     22 

Sheds  for  storing  and  sorting;  Mode  of  carrying  on  the  work  in  the  fac- 
tory; Liming:  Preparation  of  milk  of  lime  .         .         .         .         .      '  .     26 

Importance  of  the  quality  of  the  lime  used:  Testing  the  value  of  a  lime 
by  determining  the  amount  of  real  calcium  hydroxide  contained  in  it; 
Mode  of  conducting  the  operation          .......     27 

Washing  the  material  after  removal  from  the  lime  pit;  Washing  and  dry- 
ing         28 

Preservation  of  the  glue-stock  by  means  of  carbolic  acid;  Preparation  of 
carbolic  acid  solution  for  this  purpose  .......     29 

Use  of  other  antiseptics  for  the  purpose  of  preventing  putrefaction;  For- 
maldehyde and  boric  acid;  Classification  of  the  principal  varieties  of 

hides  and  leather  for  glue-stock 30 

Bones  and  cartilages         ..........     31 

Constitution  of  bones;  Composition  of  bone  cartilage;  Value  of  bones  for 

the  manufacture  of  glue;  Necessity  of  exercising  care  in  buying  bones.     32 
Sorting  the  bones;  Crushing  or  grinding  the  bones   .         .         .         .         .33 

Stamping  mill  for  crushing  bones,  described  and  illustrated      .         .         .34 
Bone  crusher,  described  and  illustrated;  Croskill  bone  mill,  described  and 
illustrated:  Sieve  for  sorting  the  crushed  bones,  described  and  illus- 
trated   36 

Lime  bath  for  bones;  Treatment  of  the  bones  with  hydrochloric  acid        .     37 
Washing  the  stock;     Use  of  dilute  sulphurous  acid  in  place  of  hydro- 
chloric acid  as  suggested  by  Gerland;  Jullion  and  Pirie's  process  for 
the  preparation  of  gelatine  from  bones  .......     33 


CONTENTS.  Vll 

PAGE 

Leather  waste;  Mechanical  manipulation  of  the  waste;  Comminution  of 
the  waste  and  use  of  a  rag-engine  or  hollander  for  this  purpose  .  .  39 

Various  methods  of  extracting  tannin  from  leather  waste          .         .         .40 

Raw  materials  for  fish  glue;  Difference  between  isinglass  and  glue  manu- 
factured from  entire  fishes;  Principal  points  to  be  observed  in  the  man- 
ufacture of  fish  glue  ..........  41 

Utilization  of  scales  of  large  fishes    .         .         .         .         .         .         .         .42 


CHAPTER  IV. 

MANUFACTURE  OF   SKIN  GLUE. 

Classification  of  operations;  Definition  of  crude  glue;  Derivation  of  the 
bulk  of  this  stock 43 

Cooking  or  boiling  glue-stock;  Boiler  for  this  purpose,  and  manner  of 
using  it  ............  44 

Duration  of  boiling  ...........     45 

Mode  of  ascertaining  the  progress  of  the  operation;  Convenient  apparatus 
for  glue-boiling  with  water,  described  and  illustrated  .  .  .  .46 

Extracting  the  glue  stock  by  the  use  of  steam  .         .         .•  .         .47 

Boiler  for  this  purpose,  described  and  illustrated;  Use  of  open-jacketed 
pans  heated  by  steam,  described  and  illustrated 49 

Process  of  cooking  as  described  by  Mr.  Thomas  Lambert;  Terne's  glue 
boiler,  described  and  illustrated  ........  51 

Clarifying  the  glue-liquor         .........     52 

Distinction  between  clearness  and  color;  Clarifying  vats;  Prevention  of 
putrefaction  of  the  liquor  .........  53 

Use  of  alum  and  other  chemicals  for  clarifying;  Freeing  the  liquor  from 
coloring  substances  ..........  54 

Use  of  animal  charcoal  for  this  purpose;  Bleaching  the  raw  materials  pre- 
vious to  boiling  them  to  glue;  Use  of  chloride  of  lime  or  of  sulphurous 
acid  for  this  purpose  ..........  55 

Forming  or  moulding  the  glue;  Moulds  for  this  purpose  .         .         .         .56 

Detaching  the  glue  from  the  sides  of  the  moulding  boxes;  Cutting  the 
cubes  of  glue  into  commercial  cakes  or  sheets;  On  what  the  shape  of 
the  cakes  depends  ..........  57 

LTse  of  stone-slabs  in  place  of  cooling  boxes;  Use  of  glass  or  zinc  plates 
for  liquors  which  in  gelatinizing  do  not  become  very  solid  .  .  .58 

Tools  for  cutting  the  jelly  into  cakes,  described  and  illustrated          .         .     59 

Machine  for  slicing  and  spreading  glue-jelly  preparatory  to  drying  in- 
vented by  Mr.  J.  Schneible,  described  and  illustrated  .  .  .  .60 

Cutting  apparatus  patented  by  M.  Devoulx,  described  and  illustrated       .     62 

Drying  the  cakes  of  glue;  Drying  in  the  open  air;  Mode  of  conducting 
the  operation  in  a  drying  room  ........  64 

Size  of  the  drying  room;  Circulation  and  change  of  air  in  the  drying 
room  .  .  .  65 


Vlll  CONTENTS. 

PAGE 

Nets  and  frames  for  drying  the  glue;  Objections  to  twine  netting  .  .  66 
Metallic  netting  and  its  advantages;  Regulation  of  the  temperature  of  the 

drying  room;  Means  of  promoting  the  dryness  of  the  air  .  .  .67 
Use  of  long  drying  galleries;  Apparatus  for  drying  glue,  invented  by 

W.  A.  Hoeveller,  described  and  illustrated 68 

Modern  drying  house,  described  and  illustrated  .  .  .  .  .71 
Method  to  accelerate  the  drying  of  glue,  proposed  by  Fleck  .  .  .72 
Mode  of  giving  the  dry  cakes  a  good  lustrous  appearance  .  .  .73 

CHAPTER  V. 

MANUFACTURE   OF   BONE   GLUE. 

Comminution  of  the  bones;  Various  methods  of  extracting  the  fat;  Boil- 
ing bones      ............     74 

Steaming  bones  and  apparatus  for  this  purpose          .         .  ~       .         .         .75 
Extraction  of  bones  with  benzine  or  carbon  disulphide;  Apparatus  for  the 
use  of  benzine  invented  by  Messrs.  Wm.  Adamson  and  Charles  F.  A. 
Simonis  of  Philadelphia,  Pa. ,  described  and  illustrated          .         .         .76 
Adamson' s  method  for  treating  substances  with  hydrocarbon  vapor  for  the 

purpose  of  extracting  oils,  fats,  etc. ,  described  and  illustrated       .         .     79 
Adamson 's  method  for  treating  substances  with  liquid  hydrocarbon  for 

the  purpose  of  extracting  oils,  fats,  etc. ,  described  and  illustrated  .         .     82 
Adamson' s  process  for  removing   hydrocarbons  from  substances  which 
have  been  treated  therewith,  described  and  illustrated  .         .         .         .84 

F.  Seltsam's  apparatus,  described  and  illustrated      .         .         .         .         .86 

F.  Seltsam's  apparatus  as  improved  by  Th.  Richter,  described  and  illus- 
trated  88 

Alfred  Leuner's  apparatus,  described  and  illustrated        .         .         .        .90 

Extraction  with  hydrochloric  acid   ........     91 

Sulphurous  acid  process   .         .         .         .         .         .         .         .         .         .92 

Generation  of  sulphurous  acid 93 

Apparatus  for  the  generation  of  sulphurous  acid  constructed  by  Dr.  Bruno 
Terne,   described  and  illustrated;    Conversion  of  cartilage  into  glue; 
Wm.  Friedberg's  apparatus  for  this  purpose,  described  and  illustrated  .     94 
Mode  of  operation  with  this  apparatus      .......     95 

Construction  of  the  filter  used  in  connection  with  the  apparatus        .         .     96 
Settling  tank,  described  and  illustrated;  Arrangement  of  an  open  evap- 
orating pan,  described  and  illustrated 98 

Cooling  the  glue  liquor;  Use  of  refrigerating  machines  for  that  purpose; 
Spiral  evaporators         ..........  100 

Vacuum  pan  for  evaporating  glue  and  gelatine  liquors,  described  and  il- 
lustrated         101 

Instrument  which  indicates  the  amount  of  dry  glue  in  the  solution,  de- 
scribed and  illustrated  ..........  103 

Process  for  the  simultaneous  utilization  of  bones  for  fat,  bone-meal  and 
glue 104 


CONTENTS.  IX 

PAGE 

Crushing  the  bones;  Apparatus  for  subjecting  the  crushed  bones  to  the 
action  of  high-pressure  steam,  described  and  illustrated  .  .  .  105 

Mode  of  operation  with  this  apparatus      .......  106 

Duration  of  steaming  the  bones  for  the  manufacture  of  animal  charcoal    .  107 

Sorting  the  bones  for  the  manufacture  of  animal  charcoal;  Former  method 
of  carbonization  ...........  108 

Arrangement  of  a  Belgian  retort-furnace,  described  and  illustrated  .         .  109 

Products  evolved  in  the  destructive  distillation  of  bones;  Mode  of  oper- 
ation with  Belgian  retort-furnaces 112 

Products  obtained  in  making  animal  charcoal  on  a  large  scale;  Process 
for  the  simultaneous  utilization  of  the  bones  for  fat,  glue  and  calcium 
phosphate;  Degreasing  the  bones  .  .  .  .  .  .  .113 

Treatment  of  the  bones  with  hydrochloric  acid;  Preservation  of  the  re- 
sulting cartilage;  Boiling  the  cartilage  in  open  vessels  ....  114 

Mode  of  extracting  the  phosphates  from  bones;  Yield  of  glue  obtained 
from  cartilage  after  extraction  of  the  mineral  constituents;  Constituents 
of  the  liquor  obtained  by  treating  the  bones  ......  115 

Utilization  of  the  liquor  in  the  manufacture  of  fertilizers  ....  116 

CHAPTEE  VI. 

MANUFACTURE   OF   PHOSPHORUS. 

Operations  included  in  the  ordinary  method  of  preparing  phosphorus; 
Burning  the  bones  to  ash;  Kiln  used  for  this  purpose  ....  117 

Improved  form  of  kiln  proposed  by  Fleck;  Mode  of  operation  with  a  kiln 
of  this  construction  ..........  118 

Quantity  of  substance  which  remains  after  burning  the  bones;  Composi- 
tion of  bone  ash ;  Conversion  of  the  bone  ash  into  a  coarse  powder;  De- 
composition of  the  bone  ash  by  sulphuric  acid  119 

Separate  processes  which  have  to  be  distinguished;  Embodiment  of  these 
processes  in  equations 120 

Actual  yield  of  phosphorus;  Methods  by  which  the  formation  of  calcium 
phosphate  may  be  effected ;  Process  without  the  assistance  of  heat  .  121 

Decomposition  of  the  bone  ash  in  the  warm  way       .....  122 

Apparatus  for  hot  lixiviation   .         .         .         .         .         .         .         .         .123 

Evaporation  of  the  liquor;  Mixing  the  fluid  with  charcoal       .         .         .   124 

Yield  of  so-called  distilling  mass;  Utilization  of  the  liquor  obtained  in 
treating  bones  for  the  manufacture  of  glue  with  hydrochloric  acid;  Con- 
centration of  the  liquor  for  crystallization  ......  125 

Mode  of  obtaining  the  calcium  phosphate  contained  in  the  mother-liquor; 
Drying  the  crystals 126 

Mixing  the  crystals  with  charcoal;  Evaporating  pans;  Treatment  of  the 
residue  of  basic  calcium  phosphate  left  in  the  manufacture  of  phos- 
phorus; Distillation  of  the  phosphorus;  Conversion  of  the  acid  calcium 
phosphate  into  calcium  metaphosphate  and  reduction  of  the  latter;  Ke- 


X  CONTENTS. 

PAGE 

torts  and  furnace  for  distilling  the  mixture  of  acid  calcium  phosphate 
and  charcoal;  The  gal  ley- furnace  .......  127 

Modification  of  the  galley-furnace,  described  and  illustrated     .         .         .  128 

Furnaces  for  the  use  of  coke  as  fuel;  Receivers  for  collecting  the  phos- 
phorus distilling  over  .  .  .  .  .  .  .  .  .  .129 

Process  of  distillation;  Indication  of  the  commencement  of  distillation     .  130 

Removing  the  phosphorus  from  the  receivers;  Regaining  the  phosphoric 
acid  contained  in  the  water  from  the  receivers;  Constitution  of  crude 
phosphorus  ............  131 

Refining  and  purifying  the  phosphorus;  Various  methods  of  purification; 
Percentage  of  loss  of  phosphorus  .  .  .  .  .  .  .  .132 

Distillation  of  the  crude  product  in  order  to  obtain  pure  phosphorus;  Re- 
torts and  distilling  apparatus  for  this  purpose,  described  and  illustrated  133 

Process  of  distillation;  Different  qualities  of  the  phosphorus  passing  over 
in  the  various  stages  of  distillation;  Separation  of  the  phosphorus  pass- 
ing over  according  to  quality  .  .  .  .  .  .  .  .134 

Moulding  the  refined  phosphorus;  Seubert's  apparatus  for  this  purpose    .  135 

Disadvantages  of  Seubert's  apparatus;  Improved  apparatus  by  which  the 
operation  is  rendered  perfectly  free  from  danger,  described  and  illus- 
trated   136 

Moulding  the  phosphorus  in  wedge-shaped  sheet-metal  boxes  .         .         .137 

Mode  of  storing  and  shipping  phosphorus;  Manufacture  of  phosphorus 
with  the  assistance  of  electricity;  Mixture  used  for  the  operation  .  138 

Furnace  employed  for  the  electrolytic  manufacture  of  phosphorus,  de- 
scribed and  illustrated  .  .  .  .  .  .  .  .  .  .139 

Mode  of  operating  the  furnace  .         .         .         .         .         .         .         .   140 

CHAPTER  VII. 

METHODS    OF    BLEACHING    GLUE. 

Bleaching  in  the  air;  Bleaching  with  chlorine          .....   141 

Bleaching  with  animal  charcoal 142 

Bleaching  with  sulphurous  acid;  Apparatus  for  the  production  of  the 
acid  solution,  described  and  illustrated 143 

CHAPTER  VIII. 

DIFFERENT  VARIETIES  OF  GLUE   AND  THEIR  PREPARATION. 

Joiner's  glue;  Material  for  the  best  variety  of  joiner's  glue      .         .         .  146 
How  to  make  and  use  glue;  Holding  power  of  glue  ....  147 

Cologne  glue    ............   148 

Russian  glue;  Additions  by  means  of  which  the  color  and  opaqueness  are 

imparted  to  this  variety  of  glue     .         .         .         .         .         .         .         .149 

Patent  glue;  Gilder's  glue;  Superior  article  of  gilder's  glue;  Size  glue 

and  parchment  glue;  Paris  glue    .         .         .  .         .  .150 


CONTENTS.  XI 

PAGE 

Liquid* glues;  Receipts  for  liquid  glues 151 

Preparation  of  saccharate  of  lime;  Steam-glue;  Russian  steam-glue;  Pale 

steam-glue;  Dark  steam-glue         .         .         .         .         .         .         .         .152 

Chrome  glue;  Glue  for  attaching  leather  to  metal;  Glue  for  leather, 

paper,  etc.     ............  153 

Glue  for  parchment  paper  in  making  sausage  skins  ....  154 

Tungstic  glue;  Indestructible  mass  for  the  manufacture  of  ornaments, 

toys,  etc.:  Compound  for  billiard  balls  ......   155 

Coloring  glue;  Process  for  this  purpose  invented  by  G.  J.  Lesser     .         .  156 
Composition  for  printing  rollers;  Size       .......  157 

Process  used  in  an  English  factory  for  making  tub-size     ....  158 

Preparation  of  bone-size;  Composition  of  the  different  grades  of  size  .  159 
Concentrated  size;  Bookbinder's  size;  Water-proof  glue;  Glue  solution 

for  rendering  wrapping  paper  water-proof     ......  160 

Water-proofing  fabrics  with  glue  and  tannin     ......  161 

Muratori  and  Landry's  process  of  water-proofing  fabrics  .         .         .         .  162 

Muzrnann  and  Krakowitzer's  process  of  water-proofing  fabrics;  Glue  for 

joints  in  leather  driving  belts;  Hectograph  mass  .....  163 
Formulas  for  hectograph  masses  .  .  .  .  .  .  .  .164 

CHAPTER  IX. 

MANUFACTURE  OF  GELATJNE,  AND  PRODUCTS  PREPARED  FROM  IT. 

Properties  of  gelatine;  Change  in  the  chemical  constitution  of  gelatine 
produced  by  concentrated  sulphuric  or  nitric  acid;  Tannin  as  a  test  for 
the  presence  of  gelatine;  Use  of  gelatine  for  culinary  and  medicinal 
purposes  ............  165 

Skin  gelatine;  Method  of  manufacture  introduced  and  patented,  in  1839, 
by  George  Nelson;  Process  patented,  in  1844.  by  Messrs.  J.  &  G. 
Cox  of  Edinburgh 166 

G.  P.  Swinborn's  improved  patented  process  for  the  preparation  of  gela- 
tine from  hides,  skins  and  glue  pieces;  Modern  process  of  preparing 
skin  gelatine;  "  Steeping"  the  skins 167 

Washing  and  bleaching  the  skins      ........  168 

Digesting  the  skins;  Clarifying  the  liquors       ......  169 

Evaporation  of  the  liquors  in  vacuo;  Drying  the  cut  cakes;  Bone  gela- 
tine; Materials  for  this  purpose;  Crushing  the  bones;  Solution  of  the 
glue  cartilage  ...........  170 

Apparatus  and  improved  manner  of  manufacture  employed  in  the  factory 
of  D.  J.  Briers,  described  and  illustrated  .  .  .  .  .  .171 

Modern  process  of  preparing  bone  gelatine 179 

Colored  gelatine;  Uses  of  colored  gelatine;  Harmless  coloring  matters; 
Colors  for  coloring  leaves  of  gelatine  with  aniline  colors  for  technical 
purposes  ............  181 

Gelatine  for  fining  purposes;  Gelatine  Lainee ;  Fining  powder  for  wine 


Xll  CONTENTS. 

PAGE 

and  beer;  Liquid  fining  gelatine;  Preparation  of  gelatine  from  ordinary 

glue 182 

Preparation  of  gelatine  for  photographic  printing  and  for  photographic 

purposes  in  general;  Kemoval  of  the  salts  from  the  gelatine  .  .  183 

Gelatine  capsules  for  medicinal  purposes;  Court  plaster  ....  184 

Gelatine  foils;  Mode  of  coloring  the  foils 185 

Gelatine  veneers;  Principal  operations  in  the  manufacture  of  gelatine 

veneers 186 

Preparation  of  the  plates;  Preparation  of  the  glue  solutions;  Proportions 

by  weight  of  the  mixtures  for  ten  different  varieties  of  imitations  of 

marble  and  enamel        ..........  187 

Imitation  of  mother-of-pearl  veneers         .         .         .         .         .         .         .  188 

Pouring  the  colored  solutions  of  glue  upon  the  plates        ....  189 

Preparation  of  imitations  of  malachite      .......  190 

Transferring  the  layer  of  glue  to  a  layer  of  gelatine  .    "     .         .         .  191 

Drying  and  detaching  the  veneers    .         .         .         .         .         .  .  192 

Water-proofing  gelatine  veneers;  Uses  of  gelatine  veneers;  Formo-gela- 

tine  and  its  uses    ...........  193 

Use  of  gelatine  in  bacteriology          ........  194 

Artificial  silk  from  gelatine  .  .  .  .  .  .  .  .  .  195 

CHAPTER  X. 

ISINGLASS    AND   ITS   SUBSTITUTES. 

Sources  of  isinglass;  Properties  of  a  good  quality  of  isinglass;  Imitations  of 

isinglass  and  their  detection;  Adulteration  of  isinglass  and  its  detection.  196 
Russian  isinglass;  Siberian  purse  isinglass;  Preparation  of  isinglass   in 

Russia 197 

North  American  or  New  York  isinglass   .         .         .         .         .         .         .198 

East  India  isinglass;  Hudson  Bay  isinglass;  Brazilian  isinglass         .         .199 
German  isinglass;  Isinglass  from  the  scales  of  shad  and  herring;  Bleach- 
ing inferior  qualities  of  isinglass;  Ichthycolle  Franchise        .         .         .  200 

Isinglassine;  Chinese  isinglass 201 

Irish  moss;  Fish  glue;  Jennings'  process  for  the  preparation  of  fish  glue.  203 
Treatment  of  fish  scales;  Production  of  fish  glue  on  the  Norwegian  coast; 

Substitute  for  isinglass  according  to  C.  A.  Sahlstrom's  process       .         .  203 
Whale  glue .  204 

CHAPTER  XI. 

TESTING   GLUE    AND   GELATINE. 

Determination  of  moisture;  Determination  of  ash;  Determination  of  acidity.  205 
Determination  of  glutin;  Bisler-Beumat's  method     .....   206 
Analysis  of  samples  of  American  glue  by  S.  Dana  Hayes;  Deduction  of 
the  quality  of  glue  from  indirect  properties  .         .         .         .         .         .  207 


CONTENTS.  Xlll 

PAGE 

Lipowitz's  method  of  testing  the  strength  of  a  glue,  described  and  illus- 
trated   208 

Results  obtained  by  comparative  experiments  ......  209 

Facts  shown  by  the  results 210 

Weidenbusch's  method  of  testing  glue      .......  211 

Preparation  of  the  plaster  of  Paris  stick  and  of  the  glue  solution  used  in 

this  test 212 

Apparatus  for  testing  the  strength  of  the  plaster  of  Paris  sticks,  described 
and   illustrated;    Test  adopted    by  the    "  Artillerie    Werkstatte"    at 

Spandau 213 

Determination  of  adulterations          ........  214 

Kissling's  results  in  testing  a  large  number  of  samples  of  glue  .         .         .  215 
Practical  tests  of  glue       ..........  216 


PART  II. 

CEMENTS,  PASTES,  MUCILAGES. 
CHAPTER  XII. 

CLASSIFICATION  OF  CEMENTS. 

Stohmann's  division  of  cements  and  pastes;  Groups  of  cements         .         .  218 
Chemical  nature  of  cements;  Oil  cements          ......  219 

Resinous  cements;  Definition  of  resins      .......  220 

Properties  of  resinous  cements  .........  221 

Rubber  and  gutta-percha  cements;  Glue  and  starch  cements  .  .  .  222 
Lime  cements 223 

CHAPTER  XIII. 

PREPARATION   OF  CEMENTS,  PASTES,   AND  MUCILAGES. 

Oil  cements;  Putty  and  its  preparation     .......  224 

French  putty;  Soft  putty;  Litharge  cement;  Red  lead  cement;  Cement 

for  wash  basins 225 

Zinc-white  cement;  Mastic  cement,  mastic  or  pierres  de  mastic  .  .  .  226 
French  mastic;  Paget's  mastic;  Water-proof  cement;  Serbat's  mastic  .  227 
Stephen's  oil  cement;  Oil  cement  for  glass;  Oil  cement  free  from  lead  for 

steam  pipes;  Oil  cements  for  steam  pipes;  Oil  cement  for  marble  .  228 
Oil  cement  for  porcelain;  Diamond  cement;  Hager's  diamond  cement; 

Resinous  cements;  Resinous  cement  for  amber;  Cement  for  turners  .  229 
Cement  for  ivory  and  bone;  Cement  for  white  enameled  clock  faces; 

Cements  for  glass;  Cement  for  glass  upon  glass;  Cement  for  glass  upon 

metal;  Cement  for  metal  letters  upon  glass;  Cement  for  wood       .         .  230 


XIV  CONTENTS. 

PAGE 

Cement  for  knife  handles;  Cement  for  petroleum  lamps;  Cement  for 
porcelain;  Cement  for  porcelain  which  is  to  be  heated;  Cement  to  with- 
stand the  action  of  petroleum;  Cement  for  mica  .....  231 

Cement  for  horn,  whalebone  and  tortoise  shell;  Cement  for  terra  cotta 
articles;  Mastic  cement  for  glass;  Stick  mastic  cement;  Sulphur  cement 
for  porcelain  ............  232 

Insoluble  cement  for  wooden  vessels;  Rubber  cements;  Cements  for  glass; 
Soft  rubber  cement 233 

Hard  rubber  cement;  Elastic  cement;  Marine  glue  .....  234 

Jeffrey's  marine  glue;  Marine  glue  for  damp  walls;  Gutta-percha  cements; 
Cement  for  leather 235 

Cement  for  hard  rubber  combs;  Elastic  gutta-percha  cement;  Cement  for 
horses'  hoofs;  Cement  for  crockery  .......  236 

Cement  for  leather;  Caseine  cements;  Preparation  of  pure  caseine    .         .  237 

Preparation  of  ordinary  technical  caseine;  John  A.  Just's  method  for 
obtaining  a  purer  technical  caseine  .......  238 

Caseine  cement  which  can  be  kept  for  a  long  time;  Cement  for  glass; 
Cement  for  metals;  Cement  for  porcelain;  Cement  for  meerschaum; 
Cement  for  wood,  etc.  ..........  239 

Cement  for  porcelain;  Water-glass  and  water-glass  cements;  Water-glass 
and  its  properties;  Cement  for  cracked  bottles  .....  240 

Cement  for  glass  and  porcelain;  Cement  for  hydraulic  works;  Cement  for 
uniting  metals;  Cement  for  tightening  joints  of  pipes  exposed  to  a  red 
heat 241 

Cement  for  marble  and  alabaster;  Glycerine  and  glycerine  cements; 
Properties  of  commercial  glycerine;  Glycerine  and  litharge  cement  .  242 

Lime  cements;  Properties  of  lime  and  chalk;  Cement  for  glass;  Cement 
for  joiners;  Cement  for  cracked  clay  crucibles  and  porcelain  .  .  243 

Lime  and  glue  cement;  Gypsum  cements;  Preparation  of  plaster  of  Paris; 
Cement  for  plaster  of  Paris  statues *  244 

Cement  for  glass  and  porcelain;  Cement  for  iron  and  stone;  Cements  for 
porcelain;  Universal  plaster  of  Paris  cement;  Iron  cements;  Heat- 
resisting  cement:  Water  and  steam-proof  cement;  Cement  for  iron  .  245 

Fire-proof  cement  for  iron  pipes;  Cements  resisting  high  temperatures; 
Cement  for  filling  in  defects  in  castings;  Cement  for  cracked  stove- 
plates,  etc. ;  Cement  for  iron  water-tanks;  Cement  for  cracked  iron  pots.  246 

Black  cement  for  stoves;  Cements  for  chemical  apparatus;  Requirements 
of  such  cements;  Cement  for  small  apparatus  to  be  used  for  the  de- 
velopment of  fluoric  acid  .........  247 

Linseed  oil  and  clay  cement;  Linseed  oil  and  manganese  cement;  Cements 
resisting  very  high  temperatures;  Cement  resisting  acids;  Rubber 
cement  for  chemical  apparatus  ........  248 

Scheibler's  cement  for  chemical  apparatus;  Cements  for  special  purposes; 
Cement  for  attaching  metal  letters  to  glass,  marble,  wood,  etc. ;  Cement 
for  joints  of  iron  pipes 249 

Steam  boiler  cement;  Cement  for  rubber;  Cement  for  tires;  Cement  for 
steam  pipes,  etc.  ...........  250 


CONTENTS.  XV 

PAGE 

Cement  for  marble;  Cement  for  attaching  wood,  glass,  etc.,  to  metal; 

Brushmaker's  cement;  Cement  for  electrical  apparatus  .  .  .  251 
Jeweler's  cement;  American  cement  for  jewelers;  Cement  for  celluloid; 

Stratena ;  Cement  for  cloth;  How  to  use  cements 252 

Importance  of  bringing  the  cement  into  intimate  contact  with  the  surface 

to  be  united 253 

Obstacles  to  the  junction  of  any  two  surfaces;  Importance  of  using  as 

little  cement  as  possible 254 

Cleansing  surfaces  to  be  joined  from  grease  and  dirt;  Paste  and  mucilages; 

Starch  paste 255 

Rules  for  preparing  paste;  Flour  paste 256 

Means  to  prevent  the  spoiling  of  paste  .  .  .  .  .  .  .  257 

Shoemakers'  paste 258 

Gum  arabic  and  its  properties;  Dextrine  and  its  use  in  place  of  gum 

arabic;  Properties  of  commercial  dextrine  ......  259 

Preparation  of  dextrine;  Blumenthal's  method 260 

Heuze's  method;  Tragacanth,  or  gum  tragacanth;  Pastes  and  mucilages 

for  special  purposes;  Starch  paste;  Flour  paste 261 

Strong  adhesive  paste;  Paste  that  will  not  sour;  Venetian  paste  .  .  262 
Label  paste;  Elastic  or  pliable  paste;  Mucilage  for  labels;  Mucilage  .  263 
Mucilage  for  postage  stamps;  Caseine  mucilage;  Tragacanth  mucilage; 

Adhesive  paste;  Fluid  pastes 264 

Sugar  and  lime  paste;  Liquid  sugar  and  lime  paste;  Pastes  for  paper  and 

fine  fancy  articles;  Albumen  paste         .......  265 

Glycerine  paste;  Paste  for  fixing  labels  on  machines;  Paste  for  mounting 

maps;    Paste  for  fastening  paper   on    tin-foil;   Paste   for  paper  bags; 

Caseine  mucilage  for  photographer's  use;  Paste  for  scrap  books  .  .  266 
Paste  for  skins;  Strong  mucilage  capable  of  fastening  wood  on  china  and 

glass;  Dextrine  mucilage;  Paste  for  joining  leather  to  paste-board  .  267 
Paste  for  attaching  labels  to  polished  nickel;  Mucilage  for  attaching 

labels  to  tin;  Mucilage  for  office  use;   Glycerine  paste  for  office  use; 

Clean  and  durable  paste 268 

Banknote  or  mouth  glue;  Paste  for  cardboard;  Paste  for  attaching  cloth 

or  leather  to  table  tops;  Caseine  mucilage;  Very  adhesive  paste  which 

may  be  used  for  wood  and  parchment   .......  269 

Paste  for  pads;  Paste  for  fastening  paper  on  tin-foil;  Paste  for  attaching 

labels  to  glass,  porcelain  and  metal;  Preparation  of  arabol-gum;  Pre- 
paration of  an  adhesive  substance  from  desaccharized  beet-root  slices  .  270 
Index  .  273 


GLUE,  GELATINE,  CEMENTS,  PASTES, 


PART  I. 
GLUE  AND  GELATINE. 


CHAPTER  I. 

NATUEE  OF  GLUE. 
1.    SOURCES    OF    GLUE. 

THE  organisms  of  all  animals,  but  more  especially  of  the 
higher  classes,  contain  tissues  which  are  insoluble  in  cold, 
as  well  aS  in  hot,  water.  However,  by  continued  boiling 
they  become  dissolved,  arid  yield  on  evaporation  of  the 
solution  a  glutinous,  gelatinizing  mass.  By  further  drying 
this  mass  exhibits,  according  to  the  degree  of  purity  of  the 
material,  a  more  or  less  transparent  and  brittle  substance, 
which  in  its  pure  state  is  devoid  of  color  as  well  as  of  smell; 
it  swells  up  in  cold  water  and  dissolves  by  boiling  in  that 
liquid.  This  substance,  i.  e.,  the  product  of  the  conversion 
of  the  so-called  glue  or  gelatine-yielding  tissue,  is  what  is 
known  in  the  trade  as  glue. 

Among  the  glue-yielding  tissues,  the  following  are  the 
most  important :  Cellular  tissue,  the  corium,  tendons  or 
sinews,  the  middle  membrane  of  the  vasa  lymphatica  and 
veins,  the  ossein  or  organic  matter  of  bones,  hartshorn, 
cartilage,  the  air  bladders  of  many  kinds  of  fishes,  etc. 

Neither  glue  nor  gelatine  exists  ready  formed  in  the  ani- 
mal organism,  except  under  abnormal  conditions  as  a 
phenomenon  of  disease,  but  they  are  the  products  of  various 


2  GLUE,    GELATINE,    CEMENTS,    PASTES. 

transformations.  The  first  of  these  transformations  evi- 
dently takes  place  in  drying  the  hide,  since  the  result  of 
boiling  to  glue  a  green  hide  prepared  in  the  usual  manner 
by  liming,  etc.,  but  not  previously  dried,  will  be  an  entirely 
different  product  of  less  consistency  than  that  obtained  by 
drying  the  hide  after  liming  and  then  boiling.  A  second 
transformation  seems  to  take  place  in  boiling  the  material,, 
and  a  third  in  drying  the  jelly  obtained,  and  this  may  ex- 
plain the  fact  that  the  latter,  which  is  not  converted  into 
actual  glue,  differs  in  its  behavior  from  glue  solution.  The 
series  of  transformation  does  not  end  even  with  the  actual 
glue,  for  it  is  a  well-known  fact  that  glue  dissolved  in  water 
and  boiled  for  some  time  does  not  gelatinize  on  cooling,  but 
remains  liquid.  We  have  here  to  deal  with  organic  com- 
binations which  are  distinguished  from  the  more  solid 
organic  compounds  by  passing  more  readily  into  decom- 
position. However,  it  is  an  established  fact  that  glue  is  an 
organic  combination  presenting  itself  in  different  modifica- 
tions. In  the  animal  organism  it  occurs  ready  formed  only 
under  abnormal  conditions  as  a  phenomenon  of  disease,  and 
hence  it  is  only  produced  by  first  drying  and  then  by  con- 
tinued boiling  of  the  glue-yielding  substance,  and  finally 
by  evaporating  and  further  drying  the  gelatinous  mass  ob- 
tained by  boiling. 

2.    TRANSITION    STAGES    OF    GLUE. 

We  therefore  distinguish : 
a.  Glue-yielding  substance. 
6.  Crude  glue. 

c.  Jelly. 

d.  Glue. 

a.  The  glue-yielding  substance  of  the  animal  body  is 
produced  from  proteine  substances,  albumen,  fibrine  and 
case'ine,  in  a  manner  similar  to  that  in  which  new  substances 
are  formed  in  the  ripening  fruit  by  the  transformation  and 
disintegration  into  constituent  parts  of  others  previously 
present. 


NATURE    OF    GLUE.  6 

b.  By  crude  glue  are  understood  glue-yielding  materials 
free  from  all  foreign  matter  and  physically  prepared  by 
drying.     It  forms  an  intermediate  link  between  glue-yield- 
ing substance  and  jelly. 

This  distinction  between  glue-yielding  substance  and 
crude  glue  is  justified  by  experience.  If,  for  instance,  fresh 
calves'  heads,  such  as  the  tanner  cuts  off  after  swelling  the 
skins,  be  carefully  limed  and  then  boiled  without  previous 
drying,  the  result  will  be  a  turbid  liquor  containing,  though 
everything  be  dissolved,  no  jelly  whatever,  or  at  least,  very 
little. 

c.  Jelly  is  obtained  by  boiling  the  crude  glue.     Its  ad- 
hesive power  is  far  less  than  thaj;  of  solution  of  finished  glue, 
and  it  will  become  more  quickly  putrid  than  the  latter. 

d.  The  finished  product  glue  is,  in  most  cases,  not  a  defi- 
nite chemical  compound,  but  a  mixture  of  substances,  with 
two  of  which  scientific  research  has  made  us  thoroughly 
acquainted. 

3.    CONSTITUTION    OF    GLUE. 

Independent  of  impurities  and  accidental  constituents, 
glue  consists  of  two  distinctly  distinguishable  combinations, 
namely,  glutin  or  gelatin  and  chondrin,  the  former  being 
formed  from  the  hide  and  osseous  parts,  and  the  latter  from 
young  bones  while  still  in  a  soft  state,  and  the  "  permanent " 
cartilages,  such  as  those  of  the  ribs  and  joints. 

The  manufacturer  has  it,  of  course,  in  his  power  to  allow 
either  of  these  substances  to  predominate  in  his  product, 
but  since  experiments  have  shown  glutin  or  gelatin  to 
possess  much  greater  adhesive  power  than  chondrin,  it  is 
advisable  to  separate  as  much  as  possible  the  cartilaginous 
matter  from  other  glue-yielding  material. 

As  an  accurate  knowledge  of  these  constituents  of  glue  is 
of  great  importance  to  the  manufacturer,  brief  reference  will 
here  be  made  to  what  scientific  research  has  made  known 
to  us  in  regard  to  them. 


GLUE,    GELATINE,    CEMENTS,    PASTES. 

Pure  glutin  or  gelatin  is  obtained  by  treating  buckshorn, 
etc.,  with  water  containing  hydrochloric  acid,  until  the 
phosphate  of  lime  which  serves,  so  to  say,  as  a  frame  for  the 
glue-yielding  substance,  is  dissolved,  and  the  organic  tissue 
called  collagen  or  ossein,  remains  behind.  After  freeing  the 
latter  from  fat  by  steeping  in  milk  of  lime  and  careful  wash- 
ing, it  is  boiled,  'and  the  resulting  jelly,  when  cold,  mechan- 
ically distributed  in  cold  water,  in  which  it  softens  but  does 
not  dissolve.  By  thoroughly  stirring  the  mass  the  glutin 
yields  its  coloring  matter  to  the  water,  the  latter  being  re- 
placed by  fresh  water  until  all  the  coloring  matter  is  ex- 
tracted. Then  pour  off  the  water  and  after  dissolving  the 
jelly  in  hot  water,  filter  the  solution  through  a  cloth.  By 
mixing  the  filtered  solution  with  an  equal  volume  of  alcohol, 
a  precipitate  of  pure  glutin  is  obtained.  By  the  precipita- 
tion with  alcohol,  the  separating  glutin  carries  down  inor- 
ganic salts,  especially  phosphates,  which  may  be  present  in 
the  solution.  To  free  it  from  them,  dissolve  it  in  a  small 
quantity  of  luke-warm  water,  acidulate  the  solution  with 
hydrochloric  acid  and  bring  it  into  a  dialyser.  The  salts 
and  the  acids  diffuse  in  the  water  which  has  from  time  to 
time  to.  be  renewed,  and  finally  a  jelly  of  pure  glutin  re- 
mains behind  ;  this  is  evaporated  to  dry  ness  in  shallow 
vessels. 

Pure  glutin,  in  a  dry  state  forms  a  glassy  substance, 
almost  colorless,  transparent  to  translucent,  brittle  or 
slightly  elastic,  free  from  odor  and  taste,  and  remains  un- 
changed in  the  air.  Its  specific  gravity  is  greater  than 
that  of  water.  It  is  neutral,  exerts  no  influence  whatever 
upon  vegetable  colors  and  is  insoluble  in  alcohol,  ether, 
hydrocarbons  or  oils.  In  cold  water  it  swells  up,  absorbing 
as  much  as  40  per  cent.,  and  becomes  opaque,  but  does  not 
dissolve.  It  dissolves  in  hot  water  and  on  cooling  forms  a 
jelly  even  if  the  solution  contains  only  1  per  cent,  of  glutin. 
It  gelatinizes  at  a  lower  temperature  than  chondrin. 

An  aqueous  solution  of  glutin  is  precipitated  by  chlorine, 


NATURE    OF    GLUE.  5 

platinic  chloride,  tannin  and  alcohol,  but  not  by  hydro- 
chloric acid,  acetic  acid,  lead  acetate,  alum  and  ferric  sul- 
phate. Concentrated  sulphuric  acid  decomposes  glutin, 
forming,  besides  other  products  of  decomposition,  chiefly 
glycocoll  and  leucine. 

When  heated,  glutin  softens,  swells  and  diffuses  an  odor 
of  burnt  hartshorn.  In  the  air,  it  takes  fire  with  difficulty, 
smokes,  flames  only  for  a  few  minutes,  and  leaves  a  bulky 
charcoal  difficult  to  incinerate,  the  ashes  of  which  consist 
principally  of  calcium  phosphate. 

Glutin,  when  in  the  jellied  state,  and  treated  with 
alcohol,  undergoes  dehydration,  under  the  influence  of 
which  it  contracts  greatly.  It  was  by  this  means  that 
Gonnor  succeeded  in  reducing  in  a  remarkable  degree  the 
size  of  a  print  obtained  in  a  very  hydrated  film  of  glutin, 
and  transferring  it,  so  reduced,  to  stone,  from  which  he  ob- 
tained a  new  impression,  quite  similar  to  the  first,  but  more 
or  less  diminished. 

By  taking  these  prints,  on  the  contrary,  with  glutin  very 
little  hydrated,  and  afterwards  steeping  them  in  water,  a 
dilatation  of  the  plate  is  obtained,  which  enlarges  the  figures 
with  the  same  regularity. 

Pure  chondrin  is  prepared  by  boiling  for  from  24  to  48 
hours  the  cartilages  of  the  ribs,  of  the  larynx  with  the  ex- 
ception of  those  of  the  epiglot,  or  of  the  windpipe  and  the 
bronchi. 

Chondrin  is  precipitated  from  its  solution  by  alcohol. 
The  precipitate  is  redissolved  in  warm  water,  evaporated, 
and  dried.  It  forms  a  semi-translucent  mass  of  a  slightly 
yellow  color  and  resembles  glutin  as  regards  fracture  and 
all  external  properties,  but  differs  from  it  in  being  precipi- 
tated from  its  aqueous  solution  by  mineral  acids,  acetate  of 
lead,  alum  and  ferric  sulphate,  and  also  by  organic  acids 
such  as  vinegar,  citric  and  oxalic  acids,  none  of  which  pre- 
cipitate glutin. 

As  regards  its  chemical  composition,  chondrin  is  poorer 


6  GLUE,    GELATINE,    CEMENTS,    PASTES. 

in  nitrogen  than  glutin,  and  contains  more  sulphur.  Its 
formula  approaches  more  closely  that  of  albumen,  which 
corresponds  also  with  the  origin  of  chondrin,  for  cartilages 
may  be  considered  as  transition-links  between  the  proteine 
and  glue-yielding  substances. 

By  the  action  of  concentrated  sulphuric  acid  upon 
chondrin,  leu  cine  is  only  produced  but  no  glycocoll.  By 
potassium  hydrate  chondrin  is  converted  into  glutin  and 
yields  then,  like  the  latter,  leucine  and  glycocoll.  By  boil- 
ing with  concentrated  hydrochloric  acid  chondrin  is  de- 
composed; a  peculiar  variety  of  fermentable  sugar,  to  which 
the  term  chondroglucose  has  been  applied,  being  formed. 

It  may  finally  be  remarked  that  chondrin  possesses  less 
adhesive  power  than  glutin  and  its  presence  in  glue  may 
be  considered  detrimental.  To  avoid  its  formation,  the  glue 
manufacturer  should  separate  as  much  as  possible  carti- 
lages from  bones.  Chondrin,  however,  is  useful  for  size. 

4.    PROPERTIES  OF  GLUE  AND  ITS  BEHAVIOR  TOWARDS    OTHER 

SUBSTANCES. 

The  product  designated  by  the  general  term  glue,  is 
always  a  mixture  of  glutin,  chondrin  and  other  substances 
not  yet  accurately  determined.  Glue  is  formed  by  evapor- 
ating and  further  drying  the  jelly,  and  its  properties  depend 
on  the  crude  glue  and  glue-yielding  material  used  for  the 
production  of  the  jelly. 

It  may  here  be  remarked  that  even  if  the  quantity  of 
glutin  contained  in  the  different  products  could  not  be  de- 
termined by  scientific  means,  the  glue  obtained  from  various 
materials  can  be  readily  distinguished  by  external  charac- 
teristics. Every  manufacturer  knows  that  hides  and  bones 
yield  a  distinct  quality  of  glue  as  regards  adhesive  power, 
elasticity  and  fracture,  and  that  the  jelly  from  glue-yielding 
substances  of  older  animals  is  more  solid  and  gives  a  larger 
yield  than  that  obtained  from  the  tissues  of  younger  and 
weaker  animals.  Glue  from  the  bladders  and  scales  of 


,       NATURE    OF   GLUE.  7 

fishes,  though  consisting  mainly  of  glutin,  differs  materially 
from  hide  or  bone  glue. 

Generally  speaking,  the  jelly,  no  matter  whether  consist- 
ing of  glutin  or  chondrin,  possesses,  before  drying  to  glue, 
different  properties  from  glue  solution.  It  has  less  adhesive 
power  and  spoils  more  quickly.  At  a  temperature  of  68° 
to  72.5°  F.,  jelly  putrefies  inside  of  24  hours,  smells  of 
ammonia,  and  decomposes,  while  glue  solution  can  be  kept 
much  longer  without  suffering  deterioration. 

The  jelly  absorbs  ozone  with  avidity  and  is  decomposed 
by  it,  this  being  the  reason  why  an  approaching  thunder- 
storm may  cause  great  damage  by  destroying  the  coagulat- 
ing power  of  the  glue  liquors,  or  causing  the  glue  to  turn 
on  the  nets,  i.  e.,  to  lose  its  consistency  and  become  liquid 
and  foul. 

The  behavior  of  glue  solution  towards  different  salts  also 
deserves  attention. 

By  adding  potassium  or  sodium  carbonate,  neutral  potas- 
sium tartrate,  Rochelle  or  Epsom  salts  to  a  lukewarm  fluid 
containing  15  to  20  per  cent,  of  glue,  the  latter  coagulates 
by  the  salt  withdrawing  the  water  from  it.  A  lukewarm 
solution  saturated  with  common  salt,  sal  ammoniac,  salt- 
petre, or  barium  chloride  does  not  gelatinize. 

By  adding  to  glue  solution  a  large  quantity  of  alum,  the 
glue  is  precipitated  as  a  transparent  mass. 

Glue  compounded  at  a  high  temperature  with  dilute 
acids,  does  not  gelatinize  by  itself,  but  will  do  so  on  adding 
common  salt. 

Boiling  with  slaked  lime  deprives  glue  solution  of  its 
power  of  gelatinizing,  and,  on  evaporation,  changes  it  into 
a  colorless  gummy  mass  which  is  soluble  in  cold  water  and 
in  saturated  solution  of  common  salt. 

From  a  glutin  solution  compounded  with  oxalic  acid,  the 
latter  can  after  some  time  be  again  separated  by  the  addi- 
tion of  lime,  the  result  being  a  non-gelatinizing  fluid  which, 
however,  possesses  great  adhesive  power.  This  is  the  so- 
called  meta-gelatin. 


8  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Glue  solution  also  loses  its  property  of  gelatinizing  by  re- 
peated boiling  and  cooling  (for  about  six  days). 

Tannin  enters  with  the  jelly,  as  well  as  with  glue  solu- 
tion, into  characteristic  combinations  which  are  formed  even 
in  solutions  containing  only  0.005  per  cent,  of  jelly  or  glue. 
Glue  is,  therefore,  an  excellent  agent  for  the  detection  of 
tannin. 

When  quite  concentrated  glue  solution  is  treated  with 
tannin,  a  heavy,  flocculent  precipitate  of  a  dirty-yellow, 
caseous  character  is  formed,  which  turns  brown  on  ex- 
posure to  the  air  and,  after  drying,  constitutes  a  hard  brittle 
mass,  easily  reduced  to  powder  and  soluble  in  hot  potash 
lye,  but  insoluble  in  water,  ether  and  alcohol.  This  pre- 
cipitate, if  not  identical  with,  is  closely  allied  to  the  com- 
bination of  tannin  with  skin,  called  leather. 

Glue  exposed  to  a  dry  heat  melts,  diffuses  a  strong  dis- 
agreeable odor  of  burned  horn  and  leaves  behind  a  charcoal 
which  has  a  powerful  discoloring  effect  like  animal  char- 
coal. When  subjected  to  destructive  distillation,  glue  yields 
an  aqueous  solution  of  ammonium  carbonate  and  a  thick 
brown  oil  consisting  of  a  mixture  of  ammonium  carbonate, 
sulphur,  ammonium  cyanide,  etc. 

The  chemical  composition  of  glue  is  such  as  to  bring  to 
mind  that  of  starch  and  cellulose  derived  from  the  vegetable 
kingdom.  It  contains : 

Carbon 49.1  percent. 

Hydrogen 6.5  per  cent. 

Nitrogen 18.3  per  cent. 

Oxygen  and  sulphur 26.1  per  cent. 

which  may  be  represented  by  the  formula :  C12H10N204. 

The  composition  of  glue  differs  but  little  from  that  of  the 
glue-yielding  substance.  Isinglass  is  composed  of  : 

Carbon 49.5  per  cent. 

Hydrogen 6.9  per  cent. 

Nitrogen 18.8  per  cent. 

Oxygen 24.8  per  cent. 


NATURE    OF    GLUE.  9 

This  justifies  the  assumption  that  glue  in  its  various 
transition  stages  does  not  represent  different  chemical  com- 
binations, but  only  modifications  of  one  and  the  same  com- 
bination distinguishable  from  each  other  by  physical 
characteristics,  as  is  the  case  with  starch,  which  without 
suffering  an  alteration  in  its  composition,  appears  as  dex- 
trine and  grape-sugar,  or  as  with  cellulose,  which,  without 
altering  its  composition,  can  be  transformed  into  amyloid 
and  grape-sugar. 


CHAPTER  II. 

USES  OF  GLUE. 

AN  inquiry  into  the  various  technical  uses  of  glue  must 
be  of  interest  to  the  manufacturer  so  as  to  enable  him, 
when  acting,  as  is  frequently  the  case,  as  salesman,  to  know 
to  whom  to  offer  his  product ;  and  also  to  learn  what  special 
demands  he  has  to  satisfy,  as  not  every  glue  is  adapted  to 
every  purpose,  different  qualities  being  required  for  special 
uses. 

Glue  as  a  joining  medium.  In  Chapter  I,  treating  of  the 
nature  of  glue,  special  attention  has  been  drawn  to  the  fact, 
that  the  adhesive  power  of  glutiii  is  greater  than  that  of 
chondrin ;  and  that  glutin  obtained  from  skin  and  tendons 
possesses  still  greater  adhesive  power  than  the  product  from 
bones.  This  is  the  reason  why  good  sound  glue  made  from 
scraps  of  skin  is  preferred  by  those  artisans  who  may  be 
considered  the  principal  consumers,  such  as  cabinet-makers, 
carpenters,  turners,  instrument-makers,  wood-carvers,  car- 
riage-builders, brush-manufacturers,  book-binders,  paper- 
manufacturers,  etc.,  all  of  them  requiring  glue  of  the  great- 
est possible  adhesive  power.  It  must,  however,  by  no 
means  be  understood  that  a  good  quality  of  bone  glue  can- 
not be  used  for  the  same  purposes ;  because  much  bone 
glue  of  excellent  quality  and  at  a  low  price  is  brought  into 
the  market  by  manufacturers  of  animal  charcoal  and  bone 
meal,  and  is  used  in  glueing  wood,  etc. 

Glue  suitable  as  a  joining  medium  for  the  above  purposes 
should  be  of  an  amber  or  brown-yellow  color,  transparent 
or  translucent,  clear,  dry  and  hard,  and  show  a  glassy  frac- 
ture which  should  not  be  brittle,  but  somewhat  elastic. 

(10) 


USES    OF    GLUE.  11 

Placed  in  cold  water  it  should  swell  up  and  absorb  as  much 
of  it  as  possible  without  actually  dissolving,  even  if  it  re- 
mains there  for  48  hours.  The  supernatant  water  should 
be  free  from  a  putrid  odor  and  contain  but  a  small  quantity 
of  foreign  substances  in  solution.  Such  glue  passes  into 
solution  at  122°  F.,  and  dissolves  entirely  on  heating  to 
144.5°  F.  Heating  to  a  higher  temperature  should  be 
avoided. 

Glue  as  a  binding  agent.  Glue  solution  is  used  for  bind- 
together  pulverulent  substances,  such  as  mineral  colors  in 
the  manufacture  of  colored  paper  and  paper-hangings,  in 
painting  in  distemper,  in  the  size  of  the  gilder ;  or  it  is 
mixed  with  plaster  of  Paris  or  chalk  for  the  manufacture  of 
plastic  masses  which  become  hard  on  drying,  such  as 
stucco-work,  papier-mache,  etc.  Generally  speaking,  it  is 
best  to  use  only  good  sound  glue  for  these  purposes,  though 
it  may  sometimes  be  possible  to  utilize  defective  and  cheap 
qualities  without  injurious  consequences.  For  color  mix- 
tures, the  glue  should  at  all  events  be  free  from  acids  and 
alkalies,  as  they  exert  a  decomposing  and  altering  effect 
upon  the  colors.  The  gilder  should  always  use  the  best 
quality  of  glue,  as  otherwise  the  work  he  applies  later  on  to 
the  size  will  spoil. 

A  very  large  quantity  of  glue  is  consumed  in  the  manu- 
facture of  matches,  and  much  depends  on  its  quality  and 
drying  properties.  The  dipping  composition  for  matches 
containing  phosphorus  is  a  bath  of  glue  of  25  to  50  per 
cent,  strength  to  which  the  requisite  amount  of  an  oxidiz- 
ing agent,  like  potassium  nitrate  or  chlorate  has  been  added, 
kept  at  a  temperature  of  100.4°  F.  The  phosphorus  is 
cautiously  put  in  ;  it  melts,  and  is  stirred  to  an  emulsion, 
when  the  sand,  glass  or  other  friction-agent  is  incorpor- 
ated. The  object  of  the  glue  is  to  protect  from  oxidation, 
without  diminishing  the  sensitiveness.  Glue  is  also  used 
as  the  binding  material  in  the  heads  and  rubbers  of  safety 
matches. 


12  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Book  binders  require  for  the  better  classes  of  work  a  glue 
which  should  naturally  be  pale  and  strong,  and  without 
marked  odor.  Some  inferior  glues  which  have  been 
chemically  bleached  turn  almost  black  in  the  pot,  owing  to 
the  bleaching  agent  not  having  been  properly  removed  or 
neutralized. 

Sand,  glass  and  emery  papers  and  cloths  are  made  by 
coating  the  surface  with  a  thin  uniform  layer  of  strong 
glue,  and  sifting  the  powder  evenly  on. 

Glue  in  sizing.  The  principal  object  of  sizing  goods  is  to 
impart  to  them  a  certain  degree  of  stiffness,  to  give  them  a 
nice  appearance  and  a  good  feel. 

As  glue  would  injure  the  color  of  white  goods,  it  cannot 
be  used  for  sizing  them,  but,  on  the  other  hand,  much  is 
employed  for  preparing  size  for  the  use  of  hat  and  cloth 
manufacturers,  weavers,  etc.  Before  the  introduction  of 
the  paper  machine  and  invention  of  rosin  glue,  animal  glue 
was  exclusively  used  for  sizing  paper,  but  at  the  present  it 
is  only  used  for  sizing  paper  manufactured  from  rags,  and 
for  pasteboard,  and  also  by  manufacturers  producing  draw- 
ing paper  sized  with  animal  substances.  The  paper,  after 
leaving  the  machine,  is  passed  through  a  glue  solution  and 
then  dried  in  the  air. 

For  actual  sizing  purposes  good  and  fine  varieties  of  glue 
are  only  used,  or  sometimes  the  manufacturers  prepare  their 
own  size  by  boiling  to  glue  dried  calves'  heads,  or  rabbit 
skins  deprived  of  their  fur,  scraps  of  parchment,  etc.  For 
cheap  woollen  hats,  glue  is  used  in  place  of  shellac.  The 
cloth  manufacturer  procures  his  glue  mostly  in  the  form  of 
a  jelly.  This  variety  of  glue  deserves  special  attention  and 
the  mode  of  preparing  it  will  be  referred  to  later  on. 

Glue  for  culinary  and  medicinal  purposes.  The  use  of 
glue  for  these  purposes  is  based  upon  three  properties  : 

1.  Upon  its  power  of  coagulating  and  inclosing  while  in 
this  state,  substances  mechanically  dissolved  and  finely 
divided  in  a  fluid,  which,  being  specifically  as  heavy  as  the 


USES    OF    GLUE.  13 

fluid  itself,  render  the  latter  turbid  and  cannot  be  got  rid 
off  by  settling.     The  glue  in  this  case  acts  as  a  clarifier. 

Large  quantities  of  isinglass  and  gelatine,  specially  pre- 
pared for  the  purpose,  are  used  for  clarifying  and  fining 
beer,  wine  and  other  liquids,  as  well  as  for  preparing 
jellies.  The  material  to  be  used  for  jellies  and  other  culin- 
-ary  purposes  must,  of  course,  be  colorless  and  entirely  free 
from  odor.  Jellies  are  made  palatable  by  flavoring  with 
spices,  sugar,  essences,  etc.,  before  congealing.  A  vegetable 
gelatine,  Agar-Agar,  which  will  be  referred  to  later  on  is 
now  brought  from  China,  and  being  cheaper  and  perfectly 
free  from  odor,  has  become  quite  a  competitor  with  isinglass 
and  gelatine. 

Prior  to  the  introduction  of  Liebig's  and  other  beef  ex- 
tracts, bouillon  tablets,  consisting  of  a  mixture  of  bone- 
jelly,  meat  broth,  extract  of  pot  herbs  and  flour,  were 
largely  used.  One  hundred  and  ten  pounds  of  meat 
repeatedly  boiled  yield  five  pounds  of  bouillon  tablets.  A 
good  meat  broth,  though  not  equal  to  that  from  Liebig's  or 
other  meat  extracts,  is  obtained  from  these  tablets  by  the 
addition  of  thirty  times  their  weight  of  water. 

If  glue  be  dissolved  in  water,  it  gelatinizes  at  the  ordi- 
nary temperature,  and  if  the  solution  be  mixed  with  other 
fluids,  for  instance,  meat  broth,  fruit  juices  and  essences, 
which  in  the  form  of  jelly  are  to  serve  as  food,  it  effects 
their  solidification. 

Glue  acts  as  a  healing  agent  by  preventing  the  access  of 
air  to  wounds.  Court  plaster  is  prepared  from  gelatine. 
When  cabinetmakers  cut  themselves,  they  apply  glue  to 
the  wound  with  the  best  success.  In  hospitals  a  com- 
pound of  gelatine  and  glycerine  is  used  as  the  best  means 
of  closing  wounds,  the  same  compound  having  also  been 
successfully  used  for  preserving  articles  of  food  such  as 
eggs,  fruit,  and  even  meat. 

Every  good  quality  of  glue  can  be  used  for  the  above 
purposes. 


14  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Medicines  of  a  disagreeable  taste  are  frequently  inclosed 
in  gelatine  capsules,  so  that  they  can  be  taken  without 
causing  inconvenience  to  the  patient.  The  use  of  these 
capsules  has  grown  to  such  an  extent  as  to  form  a  special 
branch  of  industry.  The  mode  of  manufacturing  them 
will  be  described  later  on. 

Glue  for  elastic  masses  and  as  a  partial  substitute  for  rubber. 
Glue  mixed  with  glycerine  forms  an  elastic  mass  resem- 
bling rubber.  The  same  effect  can  be  produced  by  an 
addition  of  molasses.  This  elastic  mass,  the  preparation  of 
which  will  be  described  later  on,  is  of  great  importance  for 
the  manufacture  of  printers'  rollers,  for  moulds,  etc.  Some 
manufacturers  prepare  the  mass  ready  for  use,  so  that  the 
printer  or  lithographer  need  only  remelt  it,  and  cast  it  in  a 
mould. 

Glue  is  of  great  importance  in  photolithography  as,  mixed 
with  chromium  salts,  it  is  the  only  known  means  of  trans- 
ferring a  photographic  negative  to  the  stone.  In  photo- 
graphy, gelatine  is  used  for  negative  pictures  upon  glass. 
For  the  manufacturer  of  casts  of  plaster  of  Paris  or  cement, 
this  glue  mass,  which  is  generally  used  without  an  addition 
of  glycerine,  is  indispensable  for  making  moulds  which  are 
much  undercut. 

Glue  mixed  with  glycerine  may  be  used  as  a  substitute 
for  rubber  in  manufacturing  elastic  toys,  such  as  dolls' 
heads,  animals,  etc.  For  these  purposes  it  is  advisable  to 
select  glue  which  forms  a  very  solid  jelly,  even  if  it  pos- 
sesses but  little  adhesive  power,  pure  bone-glue  being  the 
best. 

Glue  mixed  with  glycerine  (1  part  glue,  1  part  glycerine) 
is  used  as  hectograph  mass  for  the  transfer  of  matter  written 
with  concentrated  solution  of  aniline  color. 

Glue  for  fancy  articles.  Great  progress  has  been  made  in 
the  use  of  glue  and  gelatine  in  the  manufacture  of  fancy 
articles. 

The  best  known  of  all  these  products  are  perhaps  the 


USES    OP    GLUE.  15 

gelatine  foils.  They  form  thin,  transparent  sheets,  brilli- 
antly colored,  and  are  used  for  printing  sacred  images, 
visiting  cards,  labels,  etc. 

Gelatine  veneers  were  first  shown  at  one  of  the  Paris  In- 
ternational Exhibitions.  They  consist  of  sheets  varying  in 
thickness,  which  have  been  deprived  of  their  translucency 
by  an  admixture  of  colors  in  imitation  of  various  crystal- 
lization of  salts,  and  such  stones  as  lazulite,  malachite  and 
avanturine.  Glue  imitations  of  mother  of  pearl,  tortoise 
shell,  and  ivory  were  shown  which  closely  resembled  the 
genuine  articles.  These  veneers  have  been  largely  intro- 
duced in  the  manufacture  of  fancy  articles,  cabinet  ware, 
buttons,  etc.  The  most  brilliant  use  to  which  they  have 
been  put  is  in  the  manufacture  of  fans,  for  which  ivory  and 
tortoise  shell  were  formerly  used,  and  there  are  perhaps  few 
ladies  that  are  aware  that  these  glittering  toys  are  manu- 
factured from  horse  bones  from  the  knacker's  yard. 

The  successful  introduction  of  gelatine  veneers  was  soon 
followed  by  a  substitute  for  horn  in  general,  and  combs, 
buttons,  snuff-boxes,  and  hundreds  of  other  fancy  articles 
have  been  manufactured  from  these  imitations. 

In  the  foregoing  statement  only  some  of  the  principal 
uses  of  glue  have  been  enumerated,  and  there  can  be  no 
doubt  that  with  an  increase  in  the  knowledge  of  its  nature 
and  properties,  a  wide  field  is  still  open  for  progress  in  this 
industry. 


CHAPTEE  III. 

KAW  MATERIALS  AND  THEIR  PREPARATION  FOR  THE 
MANUFACTURE  OF  GLUE. 

THE  raw  materials  used  for  the  manufacture  of  glue  con- 
sist of  a  variety  of  animal  offal.  The  principal  substances 
employed  are  refuse  from  tanyards,  such  as  scraps  of  ox 
and  other  thick  hides,  the  waste  of  the  workshops  of  leather 
dressers,  morocco  leather  manufacturers,  etc.  The  tendons 
and  intestines  of  many  animals,  rabbit  and  hare  skins  de- 
prived of  their  fur,  cat  and  dog  skins,  scraps  of  parchment, 
waste  of  turners  and  button  makers,  and  offal  from  butcher 
shops  and  households,  help  to  swell  the  series  of  materials 
used  for  the  manufacture  of  glue. 

The  materials  are  collected  and  sold  either  directly  to  the 
glue  boiler,  or  to  dealers  making  a  specialty  of  glue  stock. 

As  a  thorough  knowledge  of  these  waste  products  is  of 
importance  to  the  manufacturer,  this  chapter  will  be  devoted 
to  their  detailed  description,  the  success  of  the  enterprise 
depending  largely  on  the  selection  of  the  raw  materials  and 
their  careful  sorting  and  preparation.  By  bearing  in  mind 
the  varied  products — from  the  most  ordinary  black  glue  to 
the  colorless  glassy  gelatine  for  photographic  and  culinary 
purposes — it  will  be  understood  that  entirely  different  raw 
materials  have  to  be  employed  for  the  finer  products  than 
for  the  ordinary  qualities  of  glue. 

According  to  their  derivation  the  raw  materials  may  be 
divided  into  three  groups,  namely  : 

1.  Skin-like  raw  materials :  Skin,  leather,  tissues. 

2.  Bone  raw  materials. 

3.  Materials  obtained  from  fishes  :  Air  bladders,  scales,  etc. 

(16) 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.        17 
1.    ANIMAL    SKIN. 

This  consists  of  three  layers,  namely  :  1.  The  thin  upper- 
skin — the  epidermis — which  consists  only  of  cellular  tissue, 
and  is  of  no  special  importance  for  the  manufacture  of  glue. 
2.  The  actual  leather-skin,  or  corium,  which  consists  of 
fibres  of  connective  tissue  and  forms  the  actual  object  of  the 
t-anner  as  well  as  of  the  glue  boiler.  Underneath  the 
corium  lies  the  under-skin,  which  consists  only  of  cellular 
tissue  contaminated  with  particles  of  flesh  and  fat,  which 


are  detrimental  to  the  manufacture  of  glue.  Fig.  1  repre- 
sents a  section  of  the  animal  skin.  0,  is  the  epidermis,  L, 
the  corium,  U,  the  under-skin.  The  epidermis  consists  of 
two  layers.  The  first,  superficial  one,  H,  is  known  as  the 
cuticle  or  lamellar  layer,  and  the  other  deeper  layer,  S,  as  the 
mucous  or  malpighian  layer.  The  corium  also  consists  of 
two  layers,  the  upper  one  C,  and  the  lower  one  Cv  which  is 
the  actual  leather-skin.  The  under-skin,  U,  is  an  elastic 
2 


18  GLUE,    GELATINE,    CEMENTS,    PASTES. 

tissue  containing  many  deposits  of  fat,  F,  and  perspiratory 
glands,  D,  which  are  connected  with  ducts,  Dv  with  the 
surface  of  the  skin. 

For  the  manufacturer  of  leather  and  glue,  the  corium  is 
the  only  material  of  value. 

The  tanner  trims  the  skins  before  steeping  them  in  the 
ooze.  From  sheep  and  calf  skins  he  removes  the  head  por- 
tions, it  being  more  advantageous  to  use  them  for  glue 
stock.  He  also  cuts  off  the  skin  covering  the  lower  part  of 
the  thighs,  and,  to  give  the  skin  a  neat  finish,  the  ragged 
edges  of  the  belly  part.  Of  bullock  hides,  the  ears,  tails 
and  foot  pieces  are  utilized  for  glue  stock,  while  the  head 
parts  are  tanned.  Such  tannery  waste  may  yield  44  to  46 
per  cent,  of  glue.  Scarf  skin  of  bullocks'  hides  and  waste 
in  fleshing  the  hide,  tendons  and  hinder  parts  of  cattle 
yield  from  30  to  35  per  cent.  ;  horse  sinews  from  15  to  18 
per  cent. 

Scraps  of  parchment  and  bullocks'  feet  are  highly  valued 
as  glue  stock,  since  they  are  in  fit  condition  for  boiling 
without  further  preparation.  They  may  yield  up  to  62  per 
cent,  of  their  weight  in  glue. 

Calf  and  sheep  skins  yield  a  superior  glue ;  that  from 
horse  hides  is  usually  dark  and  poor  in  quality,  although 
with  careful  working  a  strong  product  can  be  obtained  from 
the  latter. 

Of  great  value  to  the  glue  boiler  are  the  so-called  calves' 
heads,  which,  after  liming  and  drying,  form  a  special  arti- 
cle of  commerce. 

Skins  of  hogs,  hares  and  rabbits  yield  a  light-colored  glue 
of  little  consistency;  It  is,  therefore,  best  to  use  these  last- 
named  raw  materials  for  the  preparation  of  jelly,  such  as  is 
used  in  sizing,  in  the  manufacture  of  paper,  etc. 

The  older  the  animals  from  which  the  skins  have  been 
derived,  the  more  solid  the  glue  will  be.  In  many  cases, 
especially  where  a  certain  quality  of  glue  is  to  be  produced, 
it  may  be  recommended  to  separate  the  different  kinds  of 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.       19 

skin  refuse  into  lots,  provided  there  is  enough  of  each  kind 
to  boil  it  separately. 

A  considerable  number  of  skins  used  for  packing  various 
articles,  such  as  indigo  from  South  Africa,  have  been  so 
much  damaged  in  transit  as  to  render  them  useless  for  tan- 
ning, but  they  form  good  material  for  glue,  frequently 
yielding  50  to  55  per  cent. 

In  reference  to  judging  glue  stock  some  valuable  notes 
are  given  in  an  article  on  glue,  published  by  the  American 
Provision  Co.,  Chicago,  Ills.: 

"  Dry,  uncured  or  salted  stock,  such  as  raw  hide  or  South 
American,  if  soaked  for  twelve  hours  in  cold  water,  gains 
about  50  per  cent,  in  weight,  and  still  remains  tough,  and 
the  water  sweet.  The  moisture,  dirt,  and  salt  should  not 
be  over  10  per  cent. 

"  Green  salted  stock,  such  as  hide  pieces,  sinews,  calf 
heads  and  pates,  should  have  no  excess  of  salt,  nor  be  foul, 
discolored  or  heated  ;  should  be  tough,  with  the  hair  not 
loose,  and  have  a  mild  animal  odor.  Moisture  and  salt  not 
over  40  per  cent. 

"  Dry  limed  stock  soaked  twelve  hours  develops  a  char- 
acteristic odor,  and  should  be  firm,  fibrous,  and  have  no 
slimy  pieces.  The  water  should  not  be  dark.  Lime,  sand 
and  dirt,  not  over  5  per  cent. 

"  Green  limed  stock  should  be  smooth  and  soft,  any  re- 
maining hair  being  easily  detachable,  while  the  liquor 
should  be  fairly  clean,  sweet,  and  not  too  alkaline. 

"  A  large  quantity  of  waste  bones  accumulates  in  the 
preparation  of  tinned  provisions.  If  these  have  not  been 
overheated  and  are  in  good  condition,  a  considerable 
amount  of  glue  can  be  obtained  from  them,  the  bones  of 
the  head,  ribs,  and  feet  giving  a  better  yield  than  those  of 
the  thighs  and  legs. 

"  Horn  piths  should  not  contain  over  12  per  cent,  moist- 
ure, and  should  not  have  been  overheated  in  drying ;  they 
should  have  been  cleansed  from  skin  and  hair,  which  are 
of  little  value  to  the  glue-maker. 


20  GLUE,    GELATINE,    CEMENTS,    PASTES. 

"  The  age  of  the  animals  yielding  glue  stock  has  an  im- 
portant influence  on  the  product.  While  from  younger 
animals  the  product,  as  a  rule,  is  of  lighter  color,  more 
abundant  and  more  easily  obtained,  it  contains  more 
chondrin,  so  that  from  solutions  of  equal  strengths,  those 
from  mature  animals  will  be  found  to  be  of  greater  con- 
sistence and  the  glue  more  solid. 

"  Abroad,  dry  hides  are  often,  for  weighing,  soaked  in 
chlorbarium,  a  solution  of  barium  chloride,  and  then  in  a 
bath  of  dilute  sulphuric  acid,  1J  per  cent.,  which  readily 
soaks  in,  combines  with  the  barium  to  form  the  white  in- 
soluble powder  of  barium  sulphate,  leaving  weak  hydro- 
chloric acid  in  the  fibre,  to  be  afterwards  neutralized  in 
liming,  the  chloride  of  calcium  dissolving  out.  This  treat- 
ment affects  considerably  the  subsequent  making  of  glue, 
as,  beside  the  effects  of  the  acids,  the  sulphate  of  barium 
will  render  the  liquors  cloudy  and  difficult  to  clarify.  Of 
course  if  colored  glues  are  to  be  made  this  will  be  no  detri- 
ment." 

To  prevent  putrefaction,  which  is  always  accompanied  by 
decomposition  of  glue-yielding  substance  and  consequent 
loss,  the  scraps  must  be  carefully  preserved^  especially  in 
summer. 

The  tanner  prepares  the  waste  by  liming,  i.  e.,  steeping  it 
during  fifteen  to  twenty  days  in  milk  of  lime  which  is 
frequently  renewed.  By  the  action  of  the  lime,  adhering 
particles  of  blood  and  flesh  are  dissolved  and  the  fatty 
matter  is  saponified.  After  this  treatment  the  glue-stock 
is  dried. 

In  case  this  work  is  not  done  carefully  in  the  tanyard,  as 
is  only  too  frequently  the  case,  the  stock  is  of  but  little 
value  to  the  glue-boiler. 

By  allowing  the  refuse  to  lie  too  long  in  a  heap,  as  is 
sometimes  done,  putrid  fermentation  sets  in,  the  injurious 
effects  of  which  cannot  be  remedied  by  subsequent  liming, 
or  the  lime  bath  has  not  yet  been  strong  enough,  or  has  not 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.       21 

acted  sufficiently  long  upon  the  scraps  to  destroy  the  adher- 
ing particles  of  blood  and  flesh.  The  lime  bath,  on  the 
other  hand,  may  have  been  too  strong,  so  as  to  attack  the 
glue-yielding  substance.  Frequently  it  is  also  the  case  that 
the  scraps  having  been  dried  under  unfavorable  circum- 
stances, mould  has  commenced  to  form,  and  finally  they 
-may  be  spoiled  in  winter  by  allowing  them  to  freeze. 
Frozen  glue  leather  yields  glue  of  very  little  consistency. 

It  will  be  seen  from  the  foregoing  that  great  precaution 
and  care  are  required  when  buying  glue  leather.  The 
manufacturer  should  especially  see  that  it  is  dry  and  tough, 
free  from  mould  and  all  organic  and  inorganic  substances, 
and  not  too  strongly  limed. 

The  glue-boiler  should,  in  all  cases,  be  prepared  to  under- 
take the  preparation  of  the  glue  stock  himself.  The  fol- 
lowing arrangements  are  required  for  the  purpose  : 

Let  us  assume  that  the  glue  factory  is  located  on  a  stream 
of  water.  In  the  immediate  neighborhood  of  the  stream  a 
sufficient  number  of  pits  to  prepare  all  the  glue  stock  used, 
each  about  6J  feet  deep  and  6J  to  10  feet  in  diameter,  and 
lined  with  cement,  are  so  arranged  that  their  bottoms  are 
about  3  to  3 J  feet  above  the  level  of  the  water.  They  are 
supplied  with  water  by  means  of  a  pipe  line  connecting  one 
with  the  other.  Each  pit  is  provided  with  a  discharge  pipe 
to  draw  off  the  dirty  water. 

As  the  glue-stock,  before  undergoing  other  operations, 
has  to  be  freed  from  the  lime  by  washing  with  water,  the 
simplest  plan  is  to  place  the  limed  stock  in  nets  or  wicker 
baskets  suspended  in  running  water  by  means  of  a  traveling 
crane  or  other  contrivance  erected  on  the  bank  of  the 
stream.  This  elementary  method,  however,  is  open  to  sev- 
eral disadvantages,  as  it  fouls  a  large  volume  of  water  and 
may  lead  to  legal  interference,  and  its  very  simplicity  is  apt 
to  lead  to  neglect  of  precautions,  such  as  brushing  away 
solid  particles  of  lime  or  softened  animal  matters.  Further, 
the  great  quantities  of  water  carry  off  small  pieces  of  glue- 


22  GLUE,    GELATINE,    CEMENTS,    PASTES. 

stock  and  fat,  if  catch-basins  are  not  provided  sufficiently 
large  to  allow  fat,  glue-stock,  hair  and  lime  to  separate 
from  the  water. 

The  object  is  better  accomplished  and  in  a  shorter  time 
by  the  use  of  a  washing  drum.  This  consists  of  a  perforated 
iron  cylinder  about  6  feet  in  diameter  and  4  feet  in  length, 
and  open  on  both  ends.  Around  the  inside  of  the  cylinder 
are  fixed  a  number  of  wooden  shelves  6  inches  broad, 
which,  as  the  cylinder  revolves,  carry  the  glue-stock  partly 
round,  ultimately  falling  to  the  bottom  again,  the  move- 
ment dashing  it  about  under  a  spray  of  water.  In  the 
cylinder  is  also  arranged  an  iron  plate  supported  by  stays 
from  the  outside.  While  the  washing  is  in  operation  the 
plate  is  turned  perpendicular;  on  completion  it  is  brought 
to  a  horizontal  position,  forming  a  table,  on  which  the  glue- 
stock  falls,  and  the  latter  is  then  removed  to  a  hand-press 
to  squeeze  out  the  water.  The  washed  stock  is  then  re- 
moved to  the  drying  ground,  which  should  be  in  a  sunny 
and  airy  location,  and  provided  with  an  inclined  floor  of 
planks  or  cement  so  arranged  as  to  allow  of  the  admittance 
of  air  from  beneath. 

As  it  is  well  known  that  small  quantities  of  liquid,  fre- 
quently renewed  and  thoroughly  drained  off  each  time, 
effect  the  most  complete  and  economical  washing,  and  in 
the  shortest  time,  S.  Bideal  recommends  the  use  of  pits  or 
vats  with  proper  arrangements  for  stirring,  draining  and 
inspection.  The  lime  scum  from  the  pits  can  be  used  in 
the  manufacture  of  fertilizers. 

The  glue-stock  washer  shown  in  Figs.  2  to  5,  is  the  in- 
vention of  W.  A.  Hoeveler  (American  patent),  and  it  relates 
to  the  construction  of  apparatus  for  washing  glue-stock. 

In  apparatus  for  this  purpose  the  stock  is  very  commonly 
damaged  by  being  broken  up  too  much,  and  considerable 
loss  results,  besides,  from  the  fact  that  the  small  particles 
are  allowed  to  escape  with  the  wash-water.  By  the  present 
construction  and  arrangement  these  defects  are  remedied 
and  other  advantages  derived. 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.       23 


Fig.  2  is  a  transverse  vertical  section  on  line  x-x  of  Fig.  3 
of  this  apparatus ; 

Fig.  3  is  a  longitudinal  vertical  section  of  the  same ; 


FIG.  2. 


FIG.  3. 


Fig.  4  is  an  enlarged  plan   illustrating  the  screen  and 
hinged  covers,  one  being  opened  and  one  closed  ;  and 
Fig.  5  is  a  detail  of  the  hub,  stems  and  part  of  one  paddle. 


FIG.  4. 


FIG.  5. 


The  apparatus  is  constructed  in  the  form  of  a  rectangular 
trough-like  structure,  with  its  sides  and  ends,  A,  substan- 
tially water-tight  by  means  of  the  double  walls,  a  a.  The 
upper  portion  of  the  interior  is  occupied  by  the  swinging 


24  GLUE,    GELATINE,    CEMENTS,    PASTES. 

wash-box,   B,   semicircular  in   shape,   with   flat  sides  and 
rounded  bottom  throughout,  the  bottom  being  perforated. 

Upon  a  transverse  shaft,  c,  journaled  at  the  axis  of  box, 
B,  is  set  a  paddle-wheel  composed  of  a  suitable  hub,  d,  and 
adjustable  paddles,  each  composed  of  the  radial  stem,  e,  and 
the  blade,  /,  or  spoon.  The  spoons,  /,  are  set  on  the  stems, 
e,  so  as  to  be  capable  of  being  reversed  or  turned  half-way 
round,  more  or  less.  One  side  of  the  spoon,  /,  is  rounded 
off,  so  that  while  passing  through  the  stock  the  latter  will 
not  cling  to  or  remain  upon  it.  The  other  side  of  the  spoon 
is  flat,  but  slightly  skewed  or  bevelled,  so  that  when  turned 
to  face  with  the  direction  of  motion  of  the  wheel  it  not  only 
gathers  up  the  stock  and  holds  it  till  out  of  the  box,  B,  but 
upon  further  elevation  causes  it  to  roll  or  slide  along  the 
paddle  to  a  predetermined  point,  where  it  falls  off'  gently 
into  a  discharge-spout,  g,  which  carries  it  off  for  further 
treatment  practically  undamaged.  During  the  operation 
the  box,  B,  and  the  body,  A,  are  kept  supplied  by  a  stream 
of  clean  or  chemically-prepared  water,  and  the  wheel,  e  f, 
revolves  slowly  in  the  box,  the  edges  of  the  paddles  sweep- 
ing around,  while  the  box,  B,  or  its  bottom,  is  kept  oscillat- 
ing, thus  preventing  an  injurious  clogging  of  the  perfora- 
tions in  the  box-bottom.  After  the  stock  is  placed  in  the 
box,  B,  and  the  latter  filled  with  sufficient  water,  the  wheel, 
.e  /,  is  caused  to  slowly  revolve  (by  motive  or  hand  power), 
with  the  rounded  sides  of  the  spoons,  /,  presented  forward. 
This  operation  thoroughly  agitates  and  cleanses  the  stock, 
while  the  rounded  form  of  the  spoons  prevents  the  breaking 
up  of  the  natural  condition  of  the  stock.  The  inventor 
gathers  the  finer  particles  as  follows,  after  they  have  escaped 
through  the  perforated  bottom  of  the  wash-box,  B.  At  the 
lower  part  of  the  trough,  A,  elevated  on  crossbars  or  blocks, 
h,  he  places  two  parallel  strips,  i,  and  between  these,  which 
are  grooved  to  form  ways,  k,  inside,  is  set  a  long  screen,  I, 
placed  on  rollers,  m,  and  movable  thereby  on  the  rails  or 
ways,  k.  To  give  movement  to  the  screen,  I,  the  inventor 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.       25 

attaches  to  its  end  a  rod,  n,  which  projects  outwardly 
through  the  walls,  a  a,  by  means  of  the  packing-box,  p,  and 
cap  or  door,  q,  which,  when  opened,  allows  the  withdrawal 
of  the  screen,  I,  and  its  burden.  The  shaking  of  the  screen 
is  accomplished  by  a  suitable  motor  applied  to  rod,  n,  and 
is  kept  going  during  the  operation  as  required.  To  the 
strips,  i,  which  are  placed  at  a  little  distance  from  the  side 
walls,  a  (to  leave  a  passage  for  the  water  and  refuse  to  go 
through),  are  hinged  the  two  doors,  r,  which  shut  down 
upon  the  rod,  s,  as  a  support,  in  which  case  nothing  can 
fall  upon  the  screen,  or  which  open  up  and  rest  against  the 
sides,  a  a,  in  which  case  the  screen  is  exposed  and  the  side 
passages  closed  by  the  doors,  r.  During  the  initial  or 
rough-washing  stage  the  doors,  r,  are  kept  closed,  and  the 
dirty  water  and  refuse  pass  freely  down  the  side  passages 
and  out  at  a  suitable  opening  at  the  bottom.  After  this 
stage  it  becomes  desirable  to  catch  the  particles  which  get 
detached  from  the  stock  in  box,  B,  and  come  through  the 
perforations  therein.  Then  open  up  the  doors,  r,  thus  clos- 
ing the  side  passages  and  compelling  all  the  water  and 
small  stock  to  go  to  the  screen,  I,  which  catches  the  remain- 
ing stock.  When  sufficiently  accumulated  the  screen  may 
be  drawn  out  and  the  stock  thereon  removed.  When  the 
main  body  of  stock  in  box,  B,  has  been  cleansed,  the  pad- 
dles or  spoons,/,  are  reversed,  so  as  to  present  their  flat, 
skewed  faces  to  the  stock,  and  in  revolving  the  paddles  now 
gently  lift  the  stock  and  discharge  it  into  the  spout  or  hop- 
per, g.  The  washing  and  removal  of  the  stock  when  washed 
are  thus  accomplished  without  further  manipulation  than 
to  reverse  the  paddles,  which  obviously  could  be  done  by  a 
reversing-gear  on  the  motor,  thereby  reversing  the  direction 
of  movement  of  the  paddle-wheel. 

Instead  of  the  whole  box  B  being  oscillated  back  and 
forth,  its  bottom  may  be  set  on  slides  or  rollers  and  oscil- 
lated, while  the  sides  remain  stationary. 

In  the  drawings  the  box  B  is  shown  as  hung  upon  the 


26  GLUE,    GELATINE,    CEMENTS,    PASTES. 

shaft  c  as  a  centre ;  but  as  the  provision  of  means  of  recip- 
rocating or  oscillating  the  box  or  its  bottom  is  within  the 
skill  of  any  machinist,  it  is  not  necessary  to  describe  any 
specific  form.  As  the  box  with  its  contents  will  be  very 
heavy,  the  inventor  prefers  a  special  motor  for  it,  which  may 
also  be  geared  up  to  reciprocate  the  screen  /. 

Instead  of  the  door  g,  as  located  in  Fig.  2,  it  can  be 
located  as  at  q',  same  figure. 

The  entire  plant  must  of  course  be  arranged  according 
to  sanitary  regulations,  especially  as  regards  river  pollution, 
etc. 

The  sheds  for  sorting  and  storing  the  glue-stock  should, 
if  possible,  be  in  close  proximity  to  the  pits  and  washing 
drums,  and  be  dry  and  airy.  In  arranging  his  plant,  the 
glue  manufacturer  must,  in  short,  exercise  his  ingenuity 
with  a  view  to  carrying  on  the  business  with  as  little  loss  of 
material,  and  as  much  saving  of  time  and  labor  as  possible. 

The  work  in  a  factory  arranged  in  the  above  manner,  is 
carried  on  as  follows  : 

The  raw  materials  brought  by  the  dealer  are  weighed, 
and  if  in  green  state,  the  customary  percentage — generally 
50  per  cent. — taken  off.  To  facilitate  future  operations, 
and  to  enable  the  manufacturer  to  produce  different  varie- 
ties of  glue,  the  dry  materials  are  sorted  and  stored  in  dif- 
ferent compartments  of  the  store-shed. 

Green  waste,  i.  e.,  such  as  has  not  been  limed  must  be 
taken  in  hand  at  once,  as  otherwise  it  would  taint  the  air, 
be  attacked  by  rats  and  other  animals,  and  suffer  injurious 
alterations  by  decomposition.  The  manner  of  operation  is 
as  follows : 

Liming.  Prepare  "  milk  of  lime "  by  filling  the  pits, 
which  are  to  serve  for  the  reception  of  the  skin  waste,  with 
the  required  quantity  of  water  and  dissolve  in  it  2  per  cent, 
of  calcium  h}rdrate  obtained  by  slaking  a  good  quality  of 
quick  lime.  Stir  thoroughly,  and  iir  order  that  the  water 
may  become  thoroughly  saturated  with  the  lime,  let  the 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.       27 

liquor  stand  for  8  or  10  days  before  placing  the  waste  in  it. 
The  liquor  should  stand  about  9  inches  deep  over  the  waste 
in  the  pits.  The  length  of  time  the  waste  has  to  remain  in 
the  rnilk  of  lime  varies  according  to  the  material ;  calf  skins 
requiring  15  to  20  days,  sheep  skins  20  .to  30  days,  and 
heavy  ox  hides  30  to  40  days.  The  milk  of  lime  should  be 
-  renewed  once  or  twice  a  week,  and  thoroughly  stirred. 

For  the  purpose  of  liming,  the  quality  of  the  lime  used 
is  of  the  utmost  importance,  the  milk  of  lime  being 
frequently  quite  valueless  by  reason  of  having  become  car- 
bonated or  a  bad  quality  of  quick  lime  having  been  origin- 
ally employed.  It  should  be  borne  in  mind  that  only  the 
hydrate  of  lime  which  is  present  in  solution  in  lime  water 
is  of  use,  whereas  in  milk  of  lime  so  much  carbonate  and 
other  impurities  may  be  present  that  the  liquid,  though 
thick,  may  be  quite  useless.  The  value  of  a  lime  should 
always  be  tested  by  determining  the  amount  of  real  calcium 
hydroxide,  Ca(OH)2,  contained  in  it.  The  operation  accord- 
ing to  S.  Rideal,  is  conducted  as  follows :  Water  free  from 
carbonic  acid  is  first  prepared  by  boiling  distilled  water  for 
half  an  hour  in  a  strong,  round-bottomed  Bohemian  or  Jena 
flask.  While  steam  is  still  issuing,  the  flask  is  removed  for 
an  instant,  closed  by  a  well-fitting  greased  cork  or  a  rubber 
stopper,  and  allowed  to  cool.  When  the  temperature  has 
somewhat  fallen,  the  cooling  may  be  cautiously  accelerated 
by  dipping  into  a  pail  of  warm  water,  then  transferring  to 
the  cold  stream  from  a  tap.  The  water  may  be  preserved 
in  the  flask  or,  preferably,  a  number  of  bottles  with  vase- 
lined  stoppers  should  be  filled  quite  full  and  retained  for 
use. 

From  the  sample  of  lime,  well  mixed,  a  small  portion 
(about  0.25  gramme)  should  be  accurately  and  rapidly 
weighed,  placed  in  a  wide-mouthed,  stoppered  bottle  hold- 
ing about  300  cubic  centimeters,  250  Cc.  of  the  boiled 
water  added,  and  then  allowed  to  settle.  The  whole  of  the 
calcium  hydrate  will  now  have  dissolved.  Fifty  cubic 


28  GLUE,    GELATINE,    CEMENTS,    PASTES. 

centimeters  of  the  clear  liquid  should  now  be  withdrawn 
by  a  pipette,  transferred  to  a  flask,  colored  with  an  indi- 
cator— either  phenol-phthalein,  methyl-orange,  or  litmus 
may  be  used — and  its  alkalinity  determined  by  running  in 
decinormal  hydrochloric  or  sulphuric  acid  from  a  burette 
till  the  change  of  color  occurs.  Each  cubic  centimeter  of 
the  acid  corresponds  to  0.0028  gramme  of  calcium  oxide, 
or  0.0037  gramme  of  the  hydrate,  Ca(OH)2.  The  amount 
by  calculation  will  give  the  percentage  of  real  lime  present 
in  the  sample.  It  is  well  to  notice  that  any  soda  or  potash 
present  will  equally  neutralize  the  acid,  and  be  returned  as 
lime,  but  as  these  are  of  almost  equal  efficiency  their 
presence  in  small  quantity  has  no  disadvantage.  For 
special  work  it  will  be  necessary  to  have  a  full  analysis. 
As  a  rule  the  product  made  from  limestone,  or  "stone 
lime,"  is  the  best  article  in  commerce,  and  is  much  more 
free  from  stones  and  clay  than  "gray  lime"  or  "shell 
lime."  The  best  stone  lime  contains  sometimes  only  J  per 
cent,  of  impurities,  and  seldom  more  than  5  per  cent.,  while 
inferior  kinds  of  gray  lime  may  contain  as  much  as  50  per 
cent.,  and  would  be  of  little  use  in  glue-making. 

After  removal  from  the  lime  pit,  the  material  is  placed 
in  willow  baskets  or  nets,  and  immersed  in  the  stream  to 
remove  the  greater  portion  of  the  lime,  which  is  generally 
effected  in  a  few  days.  It  is  still  more  effectively  accom- 
plished by  placing  the  waste,  after  soaking  in  the  willow 
baskets,  in  the  wash  drums.  After  taking  it  from  the 
baskets  or  wash  drums  it  is  spread  in  the  drying  yard  to 
drain  and  dry,  the  desiccation  being  accelerated  by  turning 
it  over  with  a  fork  several  times  a  day.  While  drying,  the 
quick-lime  is  converted  into  carbonate,  the  latter  exerting 
no  disturbing  effect  in  the  manufacture  of  glue.  When 
sufficiently  dried,  the  material  is  ready  for  boiling,  and  the 
crude  glue  thus  obtained  can  be  stored  for  any  length  of 
time,  until  wanted  for  further  manipulation. 

In  summer  it  is  scarcely   possible   to   cleanse  the  raw 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.        29 

material  as  rapidly  as  it  is  brought  to  the  factory,  and  to 
work  it  immediately  without  putrefaction  setting  in,  and 
for  this  reason  it  would  frequently  be  risky  to  purchase 
larger  quantities  of  it,  even  if  offered  at  very  favorable 
terms.  During  the  colder  season  of  the  year,  drying  of  the 
cleansed  raw  material  is  such  a  slow  operation,  that  in 
order  to  prevent  putrefaction,  recourse  would  have  to  be 
had  to  artificial  heat. 

These  drawbacks  can,  however,  be  overcome  by  the  use 
of  carbolic  acid,  which  possesses  in  a  high  degree  the  prop- 
erty of  preventing  putrefaction.  It  is  quite  cheap,  and  as 
but  a  comparatively  small  quantity  of  it  is  required,  the 
additional  cost  need  scarcely  be  taken  into  consideration, 
since  the  value  of  glue-stock  annually  destroyed  by  putre- 
faction is  considerably  greater  than  the  expense  for  carbolic 
acid. 

The  raw  material  is  thoroughly  cleansed,  and  while  in  a 
moist  state  is  gradually  brought  into  a  brick  cistern  or 
large  vat,  carbolic  acid  solution  being  poured  over  each 
layer,  so  that,  when  the  cistern  or  vat  is  filled,  it  stands 
about  an  inch  or  two  deep  over  the  material.  The  latter 
may  be  left  in  this  state  until  wanted. 

The  carbolic  acid  solution  is  prepared  by  dissolving  2  Ibs. 
of  carbolic  acid  in  1000  quarts  of  water  ;  the  fluid  thus  ob- 
tained possessing  a  slight  odor  of  smoke.  The  washed  glue- 
stock  treated  as  above  described  with  carbolic  acid  remains 
absolutely  unchanged,  and  when  wanted  needs  only  be 
taken  from  the  cistern  and  worked  like  fresh  material. 

In  plants  having  no  running  water  at  their  disposal  and 
depending  entirely  on  well  water,  and  where  the  waste 
water  has  to  be  discharged  into  rivers  or  creeks,  water  con- 
taining carbolic  acid  should  be  used  for  all  the  washing 
operations,  a  fluid  containing  1  to  2  parts  of  carbolic  acid 
in  10,000  parts  of  water  being  sufficient  for  this  purpose. 
Such  an  addition  of  carbolic  acid  prevents  the  wash-water 
from  becoming  foul. 


30  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Carbolic  acid  has  the  tendency  of  hardening  the  glue- 
stock  and  imparting  its  odor  to  the  glue,  and  among  other 
antiseptics,  formaldehyde  and  boric  acid  have  been  recom- 
mended for  the  purpose  of  preventing  putrefaction  for  a 
reasonable  time.  Formaldehyde  in  weak  solution  (1  part 
in  10,000  to  100,000  parts  water)  has  been  found  beneficial. 
In  this  small  quantity  it  does  not  harden  the  stock  nor 
affect  the  subsequent  boiling,  as  it  is  dissipated  by  the  heat. 
Boric  acid  and  its  preparations,  notwithstanding  their  low 
antiseptic  power,  are  much  in  favor.  A  fluid  containing  1 
part  boric  acid  in  200  parts  water  will  have  to  be  used. 

The  principal  varieties  of  hides  and  leather  for  glue-stock 
may  be  classed  as  follows : 

1.  Bullock    leather    from    old    animals,    highly    limed, 
mixed  with  rump  pieces,  also  with   horse  leather,  the  latter 
being  thin,  of  a  dark  color  and  soft,  and  is  of  less  value 
than  bullock  leather,  because  it  yields  a  dark  glue.     Fat 
leather  is  bullock's  leather  from  fat,  stall-fed  cattle,  and  be- 
fore use  has  to  be  freed  from  fat  (by  means  of  benzine). 

2.  Pieces  of  hide  from   the  lower  parts  of  the  limbs  of 
cattle,  not  limed  and  with  the  hair ;  they  form  excellent 
glue-stock,  yielding  a  very  adhesive  glue. 

3.  Worn-out  hinges  from  weavers'  looms,  consisting  of 
strongest   untanned    bullock's   hide.     When    treated   with 
lime  they  yield  a  very  strong  glue,  but  are  worked  with 
difficulty. 

4.  Whip  leather.     This  is  waste  in  the  manufacture  of 
whips,  and  is  derived  from  thick  tawed  bullock  hide.     It 
yields  an  excellent,  light-colored  glue. 

5.  Calf  leather.     Broad,  thin,  translucent  strips,  slightly 
limed,  yields  glue  of  a  very  light  color. 

6.  Calves'  heads.     The  skin  of  calves'  heads,  limed,  with- 
out hair.     They  constitute  the  best  material  for  gelatine, 
and  form  a  special  article  of  commerce. 

7.  Calves'  feet.     The  skin  from  the  last  but  one  leg-joint 
which  is  cut  off  from  dry,  unlimed,  haired  skins.     It  is  the 
best  material  next  to  calves'  heads. 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.       31 

8.  Knapsack  leather.     Old  knapsacks  of  calf  skin  and 
waste  in  the  manufacture  of  new  ones,  tawed  with  the  hair 
on  with  alum  and  common  salt.     When  .suitably  washed 
this  yields  good  glue-stock.     The  alum  and  common  salt 
have  to  be  completely  removed  by  washing.     The  hair  is 
no  detriment  to  the  process  of  boiling,  it  serving  as  a  filter 
-for  the  glue  running  off.     To  this  class  belong   also    all 
kinds  of  fur  waste,  especially  remnants  of  old  fur  coats 
(sheep  skin  coats),  from  which  the  wool  is  removed  and  the 
skin  used  as  glue-stock.     All  these  materials  having  been 
treated  with  alum  and  common  salt  have  to  be  freed  from 
them  by  suitable  manipulation. 

9.  Hare  and  rabbit  skins  freed  from  their  fur.     They 
yield  a  light-colored  glue  of  little  consistency. 

10.  Cut  rabbit  skins.     In  depriving  these  skins  of  their 
fur,  they  are  cut  by  a  machine  into  fine  threads  of  even 
size.     In  France  they  are  worked  into  size  for  gilders'  use 
which  is  highly  valued. 

11.  Sheep  and  lamb  leather  (goat  leather)  limed,  thin 
and  very  light,  yields  but  a  small  quantity  of  glue  of  little 
consistency.     To  this  class  belongs  the  waste  in  the  manu- 
facture of  kid  gloves.     Waste  of  morocco  and  other  varieties 
of  similar  leather,  pressed  into  bales  and  secured  with  wire, 
comes  into  commerce  under  the  name  of  Levant  leather. 

12.  Waste  obtained  in  paring  kid    leather  and  in  the 
manufacture  of  gloves.     It  constitutes  a  flocculent  powder 
and  yields  very  thin  glue  liquor  with  slight  adhesive  power. 
Before  boiling,  the  substances  used  in  tanning  must  be  com- 
pletely removed  by  washing. 

13.  Surrons.     These  are  untanned,  unlimed  skins  of  var- 
ious wild  animals  (antelopes,  gazelles)  which  have  been 
used  for  packing  leaf  tobacco  and  various  drugs.     They 
form  good  glue  stock. 

2.    BONES  AND  CARTILAGES. 

In  addition  to  hides,  bones  are  a  material  highly  valued 


32  GLUE,    GELATINE,    CEMENTS,    PASTES. 

by  the  glue  boiler.  Chemically  speaking,  the  framework 
supporting  the  fleshy  tissues  of  the  animal  order,  and  which 
we  call  bones,  is  a  combination  of  phosphates  of  lime  and 
magnesia,  carbonate  of  lime,  and  alkaline  salts,  united  with 
fatty  and  cartilaginous  matter.  To  the  latter  we  look  for 
our  yield  of  glue  ;  to  the  fatty  matter  for  the  fat,  and  to  the 
phosphates  for  the  basis  of  fertilizers. 

Bone  cartilage  is  composed  of  carbon,  hydrogen,  oxygen 
and  nitrogen,  the  percentage  composition  being  practically 
constant,  whether  the  cartilage  be  from  an  old  or  a  young 
animal.  The  bones  of  the  young  are,  however,  much 
richer  in  cartilage  than  those  of  the  old.  This  is  reversed 
in  the  case  of  the  inorganic  or  mineral  matter,  the  old  hav- 
ing the  greatest  yield  of  phosphates. 

Then  again,  the  fatty  matters  are  more  in  evidence  in 
full-grown  animals  than  in  youth  or  age ;  also  in  the  thigh 
and  leg  bones  the  yield  is  higher  than  in  the  heads,  ribs  or 
shoulder  blades,  the  latter  averaging  12  to  13  per  cent., 
whilst  the  former  runs  18  to  19  per  cent.* 

Bones  being  less  subject  to  putrefaction  than  skin-stock, 
they  are  not  brought  into  commerce  in  a  prepared  state. 
They  are  mainly  bought  by  contract  from  various  dealers 
within  easy  access  to  the  works.  The  rates  are  generally 
fixed  for  a  certain  period,  and  cover  all  classes  of  common 
bones,  whether  fresh  butchers'  or  a  mixture  with  partly 
boiled  bones.  Bones  differ  considerably  in  their  value.  A 
fresh  bone  will  yield  the  highest  percentage  of  fat  and  glue. 
On  the  other  hand,  partly  boiled  bones  may  contain  only  6 
per  cent,  fat  with  30  per  cent,  water.  In  buying  bones  the 
manufacturer  should  exercise  great  care,  as  the  dealer 
sometimes  finds  ways  and  means  of  including  hoofs,  horns, 
iron,  beefy  matter,  and  even  pieces  of  brick.  Naturally 
they  form  weight,  but,  excepting  the  horns,  have  no  value. 

To  separate  the  different  classes  of  bone  coming  into  the 

*  Bone  Products  and  Manures.     By  Thomas  Lambert.     London,  1901. 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.       33 

works,  and  arrange  them  according  to  the  amounts  they 
would  produce  of  fat  and  glue,  is  no  doubt  a  desirable 
object,  but  in  practice  it  is  seldom  carried  out.  However, 
if  the  manufacturer  wishes  to  undertake  this  tedious  work, 
it  is  recommended  to  make  the  following  distinctions : 

1 .  Bones  of  young  animals,  sheep,  calves,  dogs,  cats,  etc., 
being  readily  disintegrated,  are  thrown  into  one  pile,  and 
also  the  light  bones  of  oxen,  such  as  skull  bones,  shoulder 
bones,  the  vertebra  of  the  tail,  etc. 

2.  A  second  pile  is  made  of  the  foot  bones  of  goats,  sheep 
and  cattle,  provided  they  can  be  had,  as  is  the  case  in  the 
United  States  and  England,  in  sufficiently  large  quantities. 

3.  Scraps  and  shavings  from  bucks'-horn  from  turners 
and  button-makers. 

4.  Thick  bones  of  oxen,  horses,  etc.,  which  must  remain 
longer  in  the  lime-bath,  together  with  waste  of  hard  bones 
from  turners. 

5.  Where  large  quantities  of  bones  are  handled  it  is  advis- 
able to  sort  out  the  bones  of  the  upper  thigh,  as  they  can 
be  more  advantageously  used  for  the  manufacture  of  piano- 
keys,   handles    for   tooth-brushes,   etc.     Hoofs,    which    are 
frequently  found,  should  be  thrown  out,  as  they  yield  no 
glue  and  can  be  utilized  for  other  purposes. 

The  further  manipulation  of  the  bones  for  the  manufac- 
ture of  glue  requires  first  of  all  their  crushing  or  grinding 
in  a  stamper  or  mill.  By  this  crushing  or  grinding  of  the 
bones  two  objects  are  attained,  namely,  they  are  more 
readily  deprived  of  their  fat  and  present  more  points  of 
attack  to  the  corrosive  agents  to  be  used  later  on.  The 
crushed  bones  are  put  in  a  large  boiler,  and  for  a  few  hours 
subjected  to  the  action  of  steam.  Leg  bones,  as  well  as 
horns,  should  not  be  boiled,  as  they  contain  no  fat,  and 
would  lose  too  much  glue-yielding  substance.  After  boil- 
ing, the  bones  are  placed  in  a  lime  vat  for  8  to  14  days. 
The  water  used  for  boiling  the  first  portion  of  bones  may 
be  used  for  a  second  one. 
3 


34  GLUE,    GELATINE,    CEMENTS,    PASTES. 

The  extracted  fat  amounting  to  4  or  5  per  cent,  of  the 
quantity  of  bones  used,  is  taken  off  the  surface  of  the  cold 
liquor  and  the  latter  may  be  utilized  as  a  fertilizer,  or  fed 
to  cattle. 

For  crushing  the  bones,  a  stamping  mill  is  generally  used, 
it  yielding,  when  properly  constructed,  material  for  the 
manufacture  of  glue,  as  well  as  granulated  bones  which 
form  an  excellent  product  for  the  preparation  of  animal 
charcoal. 

Since  animal  charcoal  in  pieces  of  quite  even  size  is  now 
in  general  demand,  it  is  recommended  to  manipulate  the 

FIG.  6. 


bones  in  the  above-described  manner,  to  sell  the  granules  to 
the  manufacturer  of  animal  charcoal,  and  use  for  boiling 
glue  only  the  completely-crushed  portions  and  the  porous 
bones  which  are  not  at  all  suitable  for  the  manufacture  of 
animal  charcoal. 

Fig.  6  shows  a  stamping  mill  very  suitable  for  the  crush- 
ing of  bones,  the  illustration  showing  the  mill  open  on  the 
left  side  and  closed  on  the  right.  It  is  furnished  with  16 
stamps,  D,  each  stamp  being  provided  with  a  cast-iron  shoe. 
The  stamps  are  lifted  by  means  of  a  cam  shaft  in  such  a 
manner,  that  the  height  of  fall  of  the  outermost  pairs  of 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.        35 

stamps  is  least  and  that  of  those  in  the  centre  greatest. 
Between  the  inner  stamps  is  a  sieve  H  with  meshes  of  suffi- 
cient size  to  allow  the  largest  pieces,  which  can  be  pro- 
duced by  granulation,  to  fall  through. 

Underneath  the  sieve  is  an  Archimedean  screw  K  for 
carrying  off  the  pieces  of  bone  passing  through  the  sieve. 

FIG.  7. 


FIG. 


The  base  of  the  stamping  mill  consists  of  iron  plates  so 
arranged  as  to  form  steps,  the  plates  lying  towards  the 
center  of  the  mill  constituting  the  lowest  steps.  Every  two 
stamps  standing  alongside  one  another  rest  upon  such  a 
step.  When  the  mill  is  set  in  motion,  the  bones  reaching 
the  stamping  trough  from  the  right  and  left  fall  upon  the 
steps,  and  are  crushed  by  the  descending  stamps. 

As  a  rule,  the  bones  to  be  stamped   are  not  brought 


36  GLUE,    GELATINE,    CEMENTS,    PASTES. 

directly  into  the  stamping  trough,  but  are  first  passed 
through  a  crushing  mill  and  the  coarser  pieces  thus  ob- 
tained are  subjected  to  the  action  of  the  stamping  mill. 

Figs.  7  and  8  show  a  well-constructed  bone  crusher.  It 
consists  essentially  of  two  cast-iron  rollers  A  and  B,  fur- 
nished with  case-hardened  cutters.  The  bones  are  intro- 
duced through  the  hopper  B,  and  the  rolls  set  in  motion  by 
means  of  cog-wheels  a  and  b.  The  bearings  of  the  roll  B 
run  in  a  carriage  which  can  be  shifted  by  the  lever-con- 
struction/^. The  object  of  this  contrivance  is  to  allow  of 
the  roll  B  giving  way  in  case  a  harder  material  than 
bones,  for  instance,  a  stone,  passes  between  the  rolls. 

FIG.  9. 


The  Crosskill  bone  mill,  Fig.  9,  as  described  by  S.  Rideal, 
is  intended  to  be  driven  by  a  strap  from  the  fly  wheel  of 
a  common  portable  engine.  It  consists  of  a  pair  of  strong 
rollers  made  of  wrought-iron  with  case-hardened  cutters, 
and  a  revolving  or  oscillating  riddle  for  separation  of  the 
ground  bones  as  they  fall  from  the  cutters  ;  the  whole  car- 
ried by  a  substantial  cast-iron  frame.  The  mill  will  grind 
from  6  to  16  hundred-weight  per  hour  with  a  three  to  eight 
horse-power  engine. 

For  sorting  the  crushed  bones  into  pieces  of  equal  size,  a 
sieve,  Fig.  10,  is  used  consisting  of  a  drum  constructed  of 
narrow  boards  covered  with  wire-netting  of  different  de- 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.       37 

grees  of  fineness.  The  upper  portion  A  of  the  drum  con- 
sists of  narrow-meshed  net  and  through  this  falls  the  fine 
meal  which  is  conveyed  by  the  Archimedean  screw  F  over 
the  frame  F  G  H  into  vessels  serving  for  its  reception. 

The  lower  section,  j#,  of  the  drum  is  furnished  with 
netting,  the  meshes  of  which  become  gradually  wider  to- 
wards the  lower  end,  and,  hence,  the  smallest  particles  of 
bone  fall  through  the  funnel,  D,  the  medium-sized  ones 
through  E,  and  the  largest  ones  through  F.  Pieces  which 
cannot  pass  through  F,  leave  the  drum  at  G. 

In  factories  manufacturing  glue  as  well  as  animal  char- 
coal, the  larger  pieces  are  steamed  by  themselves  to  obtain 

FIG.  10. 


their  fat,  and  then  charred,  while  the  small  pieces  and  the 
rneal  are  utilized  for  glue. 

The  lime-bath  used  for  bones  should  be  of  the  same 
strength  as  that  for  skin-stock.  After  removal  from  the 
lime  vat  and  washing,  the  bones  are  put  in  a  tank  of  stone 
or  wood  (brick  pits  should  not  be  used)  containing  cold 
hydrochloric  acid  of  7jJ?°  Be.  or  1.05  specific  gravity  (=  10.6 
per  cent.  HC1)  for  thick  bones,  or  half  that  strength  for 
thin  bones,  and  are  thus  left  to  digest  for  8  to  14  days, 
being  frequently  stirred  and  fresh  acid  added.  By  the 
action  of  the  acid  the  calcium  phosphate  is  dissolved  and 
the  bones  become  cartilaginous,  flexible  and  transparent. 
The  phosphates  can  be  precipitated  by  ammonia,  or  the 
whole  evaporated  with  charcoal  or  silica,  and  distilled  to 
make  phosphorus. 


38  GLUE,    GELATINE,    CEMENTS,    PASTES. 

When  sufficiently  softened,  the  stock  is  washed  in  wicker 
baskets  or  a  washing  drum  to  remove  adhering  acid.  They 
are  then  placed  for  one  day  in  the  lime  liquor,  again 
washed,  and  then  either  dried  or  stored  away  for  future  use, 
or  boiled  at  once  to  glue,  while  in  a  moist  state. 

Leg  bones,  horns,  and  other  soft  bones  which  contain 
scarcely  any  fatty  matter  are  not  steamed  for  the  reason 
previously  stated,  but  in  all  other  respects  are  treated  like 
steamed  bones. 

It  is  of  the  greatest  importance  that  the  bones  should  be 
thoroughly  freed  from  acid,  since  even  the  smallest  quan- 
tity remaining  behind  exerts  an  injurious  effect  upon  the 
finished  glue.  It  is  therefore  recommended  to  test  the 
water  draining  off,  or  the  bones  themselves,  with  litmus. 
If  the  tincture  turns  red,  it  is  a  sure  indication  of  the  pres- 
ence of  free  acid,  and  the  washing  must  be  continued  until 
the  blue  color  of  the  tincture  remains  constant. 

Gerland's  suggestion,  to  use  dilute  sulphurous  acid  in 
place  of  hydrochloric  acid  for  dissolving  the  phosphates  of 
the  bones,  and  to  evaporate  the  sulphurous  acid  by  heat- 
ing, whereby  the  phosphates  are  precipitated  in  an  insol- 
uble state,  has  now  been  quite  generally  introduced. 

For  the  preparation  of  gelatine  from  bones,  Jullion  and 
Pirie's  process  may  be  recommended.  It  requires  a  some- 
what expensive  plant,  but  saves  hydrochloric  acid  and 
time.  The  process  consists  essentially  in  dissolving  the 
phosphates  of  the  bones  in  vacuum.  A  box  of  wood,  or 
better  of  granite,  which  can  be  closed  air-tight,  is  required 
for  this  purpose.  The  box  is  filled  with  bones,  and  acid  of 
the  previously-mentioned  strength  poured  over  them.  The 
box  is  then  closed  and  the  air  pumped  out  by  water  or 
steam  power.  The  smallest  cracks  and  pores  of  the  bones 
are  thus  freed  from  air,  and  the  latter  is  replaced  by  hydro- 
chloric acid,  which  in  this  manner  acts  rapidly  and  is  com- 
pletely exhausted.  The  remaining  crude  glue  is  then 
further  worked  in  the  usual  way. 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF  ,GLUE.        39 

Bones  honeycombed  by  putrefaction,  exposure  to  the 
weather,  or  burial  in  the  ground  are  of  little  or  no  value  to 
the  glue-boiler,  as  nearly  all  the  glue-yielding  substance  has 
been  destroyed ;  they  should  therefore  be  thrown  out  in  buy- 
ing stock.  The  ammonia  which  is  formed  when  putre- 
faction sets  in,  colors  the  glue  dark. 

3.    LEATHER    WASTE. 

Leather  tanned  with  a  substance  insoluble  in  water  is  not 
directly  suitable  for  manufacturing  glue,  but  can  be  made 
so  by  a  special  process,  which,  though  somewhat  tedious, 
nevertheless  pays  for  the  trouble. 

In  using  such  stock  the  manufacturer  should  make  a  dis- 
tinction between  old  and  new  leather.  The  principal 
materials  of  this  kind,  large  quantities  of  which  contribute 
their  quota  to  the  glue-boiler's  stock,  are  old  shoes,  straps, 
harness,  etc.,  and  further,  waste  from  shoemakers,  trunk- 
makers,  and  in  fact  from  the  shops  of  all  workers  in  leather 
except  those  using  alumed  leather. 

Before  boiling  the  leather  waste  to  glue,  the  removal  of 
^11  traces  of  tannin  becomes  absolutely  necessary,  since  the 
retention  of  the  smallest  quantity  prevents  the  animal  tissue 
from  dissolving  in  water. 

The  various  methods  proposed  for  the  preparation  of  the 
leather  waste  differ  either  in  the  chemical  solvent  used,  or 
in  the  mechanical  manipulation  of  the  waste. 

The  principal  point  in  all  methods  is  to  comminute  the 
waste  as  uniformly  as  possible  to  facilitate  the  complete  re- 
moval of  the  tannin. 

Various  machines,  some  very  complicated,  have  been 
proposed  for  the  comminution  of  the  waste,  but  a  rag  engine 
-or  "  hollander  "  such  as  is  used  by  paper-makers  deserves 
preference  for  the  purpose,  as  it  not  only  comminutes, 
washes  and  prepares  the  waste  in  a  suitable  manner  for  the 
manufacture  of  glue,  but  the  leather  pulp  when  mixed  with 
rags  or  woody  fibre  gives  a  substitute  for  leather  which  is 


40  GLUE,    GELATINE,    CEMENTS,    PASTES. 

very  tough  and  of  good  appearance,  and  can  be  worked  into 
many  articles. 

After  the  preparation  in  the  hollander  and  careful  wash- 
ing the  waste  is  treated,  according  to  Stenhouse,  under  a 
pressure  of  two  atmospheres  in  a  boiler  with  water  to  which 
is  added  15  per  cent,  of  the  quantity  of  waste  to  be  treated 
at  one  time  of  slaked  lime. 

By  another  method  the  extraction  of  the  tannin  is  effected 
by  boiling  the  leather  pulp  with  caustic  soda  of  1.025  spe- 
cific gravity  for  from  six  to  twelve  hours.  After  drawing 
off  the  water  and  pressing  out,  the  pulp  is  again  boiled  with 
caustic  soda  of  the  same  concentration.  The  next  process 
is  to  carefully  wash  out  the  soda,  which  is  best  effected  in 
the  hollander. 

By  neutralizing  the  soda  lye  in  the  fluid  drawn  off  after 
the  first  boiling,  it  can  be  re-used  for  tanning  or  purposes 
for  which  tannin  is  required. 

According  to  another  method,  the  modus  operandi  is  as 
follows : 

Dissolve  1 J  Ibs.  of  oxalic  acid  in  3  gallons  of  water,  pour 
the  boiling  solution  over  110  Ibs.  of  waste,  and  keep  the 
mixture  in  a  water-bath  at  a  temperature  of  176°  to  212°  F. 
This  effects  the  solution  of  the  pulp.  Then  dilute  the  solu- 
tion by  adding  gradually  4  gallons  of  water  until  a  uniform 
mass  is  formed.  Now  add  5  Ibs.  of  lime  slaked  to  a  thin 
paste,  and  mix  the  whole  thoroughly.  The  mass  becomes 
friable  and  pulverulent.  It  is  passed  through  a  wire  sieve 
and  then  exposed  to  the  air.  In  three  to  four  weeks  the 
tannin  is  entirely  destroyed,  which  is  recognized  by  the 
mass  assuming  a  lighter  color.  The  lime  is  then  removed 
by  washing  with  water  and  hydrochloric  acid.  If  the  tan- 
nin has  not  been  entirely  destroyed  by  exposure  to  the  air, 
add  1  Ib.  of  liquid  ammonia  and  a  like  quantity  of  pyrolu- 
site  to  every  110  Ibs.  of  leather  substance  when  boiling  it  to 
glue.  The  oxygen  yielded  up  by  the  pyrolusite,  which,  in 
the  presence  of  ammonia,  exerts  no  injurious  effect  upon  the 


RAW    MATERIALS    FOR    THE    MANUFACTURE    OF    GLUE.       41 

glue,  destroys  the  last  traces  of  tannin.  Frequent  stirring 
with  a  shovel  while  the  material  is  exposed  to  the  air  and 
moderate  heating,  facilitates  the  destruction  of  the  tannin. 

4.    RAW  MATERIALS  FOR  FISH  GLUE. 

The  air-bladders  or  sounds  of  various  fishes  contain  much 
glue-yielding  substance  and  on  account  of  its  purity,  the 
product  known  as  isinglass  obtained  from  them  is  preferably 
used  for  culinary  and  medicinal  purposes.  The  high  price 
of  the  raw  material  excludes  it  from  being  used  by  the 
glue-boiler,  but  as  he  manufactures  substitutes  for  isinglass, 
and  should  therefore  have  a  thorough  knowledge  of  the 
article  with  which  he  has  to  compete,  its  manufacture  will 
be  included  in  this  treatise.  Since,  however,  the  work  of 
the  manufacturer  is  finished  with  the  preparation  of  the 
raw  material,  i.  e.,  of  the  air-bladders  into  crude  glue,  isin- 
glass and  its  substitutes  will  be  referred  to  later  on. 

There  is  a  material  difference  between  isinglass  and  glue 
manufactured  from  entire  fishes.  The  raw  material  is,  of 
course,  limited  to  certain  localities.  The  principal  point  to 
be  observed  in  the  manufacture  of  fish-glue  is  the  removal 
of  the  skin,  which  is  effected  by  means  of  dilute  sulphuric 
acid. 

After  removal  of  the  last  traces  of  acid,  the  fatty  matter 
of  the  fishes  is  saponified  by  a  treatment  with  milk  of  lime 
frequently  renewed.  After  washing  out  the  lime,  the  pulpy 
mass  is  placed  in  a  solution  of  sodium  hyposulphite,  alum, 
and  common  salt,  where  it  remains  for  a  few  days.  The 
liquor  is  then  drawn  off  and  replaced  by  a  mixture  of  solu- 
tion of  alum,  dilute  sulphuric  acid  and  nitric  acid.  After 
macerating  in  this  mixture  for  a  few  days,  the  mass  is 
thoroughly  washed  and  boiled  to  glue,  and  the  resulting 
product  clarified  with  sulphurous  acid  or  alum  solution. 
As  will  be  seen,  the  entire  process  is  tedious,  requires  many 
chemicals,  and  besides  the  yield  of  glue,  which  has  no 
specially  good  qualities,  is  small.  It  is  used  as  a  substitute 


42  GLUE,    GELATINE,    CEMENTS,    PASTES. 

for  isinglass  for  clarifying  liquids.  The  best  proof  that  the 
business  is  of  but  little  importance  is  found  in  the  fact  that 
no  fish-glue  has  been  exhibited  at  any  of  the  late  inter- 
national exhibitions. 

The  scales  of  large  fishes,  such  as  carp,  give  more  favor- 
able results.  They  are  treated  with  hydrochloric  acid  in  a 
similar  manner  to  bones.  The  scales  do  not  dissolve  en- 
tirely, a  horny  insoluble  mass,  giving  no  glue,  remaining 
behind  after  the  solution  of  the  glue-yielding  substance. 


CHAPTER.  IV. 

MANUFACTURE  OF  SKIN  GLUE. 

The   thorough    preparation   of  the   raw   materials 
materially  facilitate  all  succeeding  operations,  which  may 
be  classified  as  follows  : 

1.  Boiling  the  glue. 

2.  Clarifying  the  glue-liquor. 

3.  Forming  or  moulding  the  glue. 

4.  Drying  the  glue. 

However,  before  entering  into  the  description  of  these 
operations,  it  will  be  necessary  to  refer  to  an  intermediate 
product,  which  has  been  previously  mentioned  under  the 
name  of  crude  glue,  and  is  prepared,  for  instance,  by 
tanners  and  manufacturers  of  parchment,  but  also  forms  in 
some  localities  a  special  branch  of  industry. 

This  crude  glue  is  actually  not  glue,  but  a  glue-yielding 
substance  in  such  a  state  of  preparation  that  it  can  be 
directly  used  for  the  first  operation,  namely,  boiling.  It 
consists  of  waste  of  skins  and  leather  of  all  kinds,  com- 
pletely cleansed,  dried  and  limed,  and  in  the  case  of  leather 
treated  with  agents  for  the  extraction  of  the  substances  used 
in  the  tanning.  As  will  be  readily  understood,  the  operations 
required  for  the  preparation  of  this  stock  are  virtually  the 
same  as  those  described  in  the  previous  chapter  for  raw 
materials  and  need  not  further  be  here  referred  to. 

The  bulk  of  such  stock  is  prepared  by  tawers  and  manu- 
facturers of  parchment,  though  a  considerable  quantity  of 
it  is  also  derived  from  waste  in  the  manufacture  of  gloves. 
The  product  from  the  latter  source  is  also  found  in  com- 
merce under  the  French  names  Colle  franche  or  Brochette. 
However,  if  such  stock  is  used,  it  is  best  to  again  immerse 

(43) 


44  GLUE,    GELATINE,    CEMENTS,    PASTES. 

it   in   lime   water,  after   which   it   should   be   thoroughly 
washed. 

The  manufacture  of  glue  from  hide  and  leather  waste 
differs  materially  in  many  respects  from  that  of  bone  glue, 
it  being  the  more  simple  process,  as  no  other  preliminary 
operations  than  the  preparation  of  the  glue-stock  are  re- 
quired. The  first  operation  is 

1.    COOKING    OR    BOILING. 

For  this  operation  any  kind  of  boiler  may  be  used,  but 
the  materials  should  be  supported  on  a  perforated  grid  a 
little  distance  above  the  bottom,  so  as  to  save  them  from 
risk  of  scorching.  In  the  centre  of  the  grid  stands  a  conical 
pipe  2  to  3J  feet  long,  perforated  like  the  grid  and  commu- 
nicating with  the  space  between  the  grid  and  the  bottom  of 
the  boiler.  The  height  of  the  boiler  can  be  increased  1  to 
1J  feet  by  placing  an  annular  piece  upon  the  rim  which  is 
bent  upwards  for  its  reception. 

The  size  of  the  boiler  depends  on  the  quantity  of  raw 
material  to  be  worked  at  one  time.  It  is  best  to  choose 
boilers  holding  from  110  to  440  Ibs.  of  glue-stock,  and  to 
place  two,  four  or  more  of  such  boilers  in  one  hearth. 

The  manner  of  using  such  a  boiler  is  very  simple.  Straw 
is  placed  upon  the  false  bottom  in  such  a  manner  as  to  cover 
its  entire  surface,  and  extend  up  the  sides  of  the  boiler  at 
least  as  far  as  it  is  touched  by  the  flame.  The  object  of  the 
straw  is  to  serve  as  a  filter,  and  protect  the  materials  from 
injury  by  the  flame.  But  for  the  production  of  entirely 
pure  gelatine  or  glue,  straw  cannot  be  used,  as,  by  boiling,  it 
yields  a  yellow  coloring  matter,  which  passes  into  the  glue. 
Barley  straw  gives  a  less  intense  coloring  matter  than  rye 
straw. 

In  case  straw  cannot  be  used,  the  material  is  placed  in  a 
large  bag,  previously  thoroughly  boiled,  and  suspended  in 
the  boiler  so  as  not  to  touch  the  sides.  By  this  means 
scorching  is  prevented  even  if  the  fire  touches  the  bottom 
as  well  as  the  sides  of  the  boiler. 


MANUFACTURE    OF    SKIN    GLUE.  45 

The  boiler  having  been  heaped  with  material  so  high  as 
to  overflow  the  brim  and  fill  the  annular  piece  placed  upon 
it,  is  filled  with  water  as  far  as  touched  by  the  fire.  The 
fire  may  now  be  started.  The  hearth  in  which  the  boiler 
is  placed  should,  of  course,  be  so  constructed  that  the  gases 
are  uniformly  distributed  and  the  water  quickly  brought  to 
the  boiling-point.  When  the  water  commences  to  boil, 
bubbles  of  steam  ascend  from  the  space  beneath  the  grid 
and,  passing  through  the  perforations  of  the  conical  pipe, 
penetrate  the  glue-stock.  Thus  the  first  formation  of  glue 
takes  place,  and  the  stock  begins  to  settle  down  gradually 
as  it  goes  into  solution.  The  stock  heaped  up  in  the  an- 
nular piece  also  sinks  down  gradually,  and  being  partly 
heated  by  the  hot  vapors  and  thus  prepared  for  solution,  is 
finally  submerged  in  the  boiling  solution  and  becomes  soon 
entirely  dissolved. 

Waste  of  hide  and  horn  piths  are  completely  dissolved  in 
five  to  seven  hours.  No  more  water  should  be  used  than  is 
absolutely  required  for  cooking  the  entire  quantity  of  stock, 
because  too  much  water  renders  the  solution  too  thin  and 
gives  a  jelly  of  little  consistency  and  difficult  to  dry.  Con- 
centrating the  glue  solution  by  continued  boiling  is  bad 
practice,  as  it  is  detrimental  to  the  resulting  product  by 
reason  of  the  glutin  undergoing  a  gradual  transformation. 

It  is  best  to  start  with  a  slow  fire  to  give  the  stock  time 
to  soften  and  thus  prepare  it  for  solution.  When  somewhat 
softened,  the  mass  is  brought  to  boiling  and  the  latter  kept 
up,  gently  and  uniformly,  until  solution  is  complete.  Solu- 
tion is  promoted  by  careful  stirring,  but  care  should  be  had 
not  to  disarrange  the  straw  upon  the  grid  and  on  the  sides 
of  the  boiler  as  this  would  interfere  with  proper  filtration  of 
the  glue  solution. 

The  duration  of  cooking  depends  on  the  nature  of  the  raw 
materials.  Scraps  of  skin  from  young  animals,  antlers, 
sheep  trotters,  etc.,  dissolve  in  three  to  four  hours,  while 
waste  from  ox  and  horse  hides,  or  bones  from  old  animals, 
require  six  to  eight  hours. 


46  GLUE,    GELATINE,    CEMENTS,    PASTES. 

The  progress  of  the  operation  is  readily  ascertained  by 
pouring  a  small  sample  of  the  gelatinous  fluid  in  half  an  egg- 
shell, and  setting  it  aside  for  a  few  minutes  to  cool.  If  a 
clear  and  consistent  jelly  be  obtained,  boiling  has  been 
carried  on  to  a  sufficient  extent,  and  the  liquid  is  drawn  off. 
Any  undissolved  glue-stock  remaining  upon  the  straw  filter 
can  be  boiled  by  itself,  and  the  resulting  gelatinous  liquor 
utilized  in  the  next  boiling. 

It  is  evident  that  quick  and  uniform  solution  of  the 
materials,  which  enhances  the  quality  of  the  glue,  is  pro- 
moted by  comminuting  the  glue-stock  either  by  grinding, 
stamping,  or  mechanical  means. 

The  succeeding  clarification  of  the  glue  is  much  facili- 
tated by  removing  while  boiling  the  scum,  consisting  of 
fat,  coagulated  albumen,  lime-soap,  accidental  admixtures, 
and  other  impurities.  Before  drawing  off  the  gelatinous 
liquor  it  is  advisable  to  withdraw  the  fire  and  allow  the 
contents  of  the  boiler  to  rest  for  fifteen  minutes. 

The  residue  remaining  upon  the  straw  filter  consists  of 
hair,  lime-soap,  undissolved  particles  of  hide  and  bones, 
lime,  etc.,  and  is  utilized,  after  repeated  boiling,  as  fertilizer 
or  for  the  manufacture  of  gas. 

The  mode  of  glue  boiling  above  described  is  the  oldest  and 
at  present  is  only  in  use  in  small  establishments.  Fig.  11 
represents  a  convenient  apparatus  for  the  purpose.  It  con- 
sists of  three  boilers  upon  as  many  different  levels.  The  lower 
boiler,  b,  serves  for  the  settling  and  clarification  of  the  glue. 
It  communicates  with  the  second  boiler,  a,  which  contains  the 
material  to  be  acted  on,  by  means  of  a  pipe  provided  with 
a  stopcock,  and  is  sufficiently  heated  by  a  small  fire  to  keep 
the  glue  liquid  without  allowing  it  to  reach  ebullition.  The 
upper  boiler,  c,  which  is  heated  by  the  waste  heat  of  the 
chimney,  serves  as  an  economical  reservoir  for  hot  water. 
The  end  of  the  discharge-pipe  of  the  settling  boiler  is  pro- 
vided with  a  filter  of  woven  wire.  As  the  sides  and  bottom 
of  the  second  boiler  are  lined  with  straw,  which  acts  as  a 


MANUFACTURE    OF    SKTN    GLUE. 


47 


preliminary  filter,  the  glue  runs  off  quite  clear  from  the 
settling  boiler. 

When  this  mode  of  manufacture  is  adopted,  two  boilings 
can  be  made  per  day,  under  favorable  circumstances,  so 
that,  if  the  boiler  has  a  capacity  of  220  Ibs.  of  stock,  which 

FIG.  11. 


will  yield  from  110  to  132  Ibs.  of  dry  glue,  the  daily  fabri- 
cation will  be  about  220  Ibs.  of  finished  product. 

In  larger  plants,  the  above  described  mode  of  extracting 
the  glue-stock  with  water  has  been  superseded  by  the  use 
of  steam  in  a  cylindrical  wrought-iron  boiler,  twice  as  high 
as  wide,  and  capable  of  withstanding  a  pressure  of  three 
atmospheres.  The  boiler  is  furnished  with  a  perforated 
false  bottom  underneath  which  terminates  a  steam  pipe.  It 
is  filled  from  above  with  previously  softened  glue-stock  and 
the  charging  hole  hermetically  closed.  Steam  is  then 
gradually  admitted  and  exerts  at  once  a  dissolving  influence 
upon  the  stock.  A  portion  of  the  steam  condenses  and 
forms  with  the  dissolved  glue-stock  a  concentrated  jelly 
which  collects  between  the  true  and  false  bottoms. 


48 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


For  the  escape  of  air  a  cock  is  provided  which  is  closed 
as  soon  as  steam  commences  to  escape  from  it. 

The  advantages  of  this  process  are  obvious.  A  larger 
quantity  of  glue-stock  can  be  extracted  than  in  the  boiler 
previously  described,  and  there  is  no  danger  of  injury  by 
scorching  and  consequent  damage  to  the  color  of  the  glue. 
More  highly  concentrated  solutions  are  obtained  in  a  shorter 
time,  and  the  spoiling  of  the  glue  solution  by  too  long  con- 

FIG.  12. 


tinued  cooking  is  prevented  by  drawing  off  the  solution  as 
quickly  as  formed.  The  escaping  hot  vapors  may  be  util- 
ized for  drying  the  glue,  softening  the  raw  material,  etc., 
the  entire  quantity  of  heat  being  thus  utilized.  A  further 
great  advantage  of  this  method  is  that  there  is  less  annoy- 
ance from  badly-smelling  vapors  than  when  boiling  is  done 
over  an  open  fire.  A  number  of  such  boilers  can  be  ar- 


MANUFACTURE    OF    SKIN    GLUE.  49 

ranged  in  one  room  and  supplied  from  a  common  steam 
boiler. 

Fig.  12  represents  a  boiler  for  extracting  glue-stock  with 
the  use  of  steam.  It  is  provided  with  a  lid,  D,  which  is 
removed  for  charging  the  boiler.  The  aperture,  E,  in  front, 
serves  for  the  removal  of  the  residue.  Above  the  true  bot- 
tom there  is  another  false  bottom,  perforated  and  movable, 
which  can  be  covered  with  straw  for  preliminary  filtration. 
The  steam  reaches  the  glue-stock  through  a  pipe  which 
passes  through  the  actual  and  false  bottoms,  and  is  per- 
forated above  the  latter.  The  resulting  jelly  collects  be- 
tween the  true  and  false  bottoms,  where  it  is  less  exposed 
to  the  action  of  hot  steam.  The  escaping  steam  passes 
through  the  pipe,  jP,  which  is  provided  with  a  stock-cock. 
The  pressure  in  the  boiler  is  indicated  by  the  manometer, 
K.  After  throwing  the  materials  into  the  boiler  they  can 
be  covered  with  warm  water,  or,  after  the  lid  is  closed, 
warm  water  is  introduced  from  a  reservoir  through  a  spe- 
cial pipe  and  distributed  over  the  material  through  a  rose. 

The  boiler  stands  upon  a  frame  sufficiently  high  to  allow 
of  conveniently  placing  a  vessel  under  the  pipe  G,  through 
which  the  jelly  is  discharged.  The  vessel,  when  full,  is 
•conveyed  to  the  settling  vat,  or  the  arrangement  may  be 
such  that  the  jelly  is  directly  run  into  the  settling  vat. 

In  many  large  plants  open  jacketed  pans  heated  by  steam 
are  still  used  for  treating  the  material.  Fig.  13  shows  an 
arrangement  with  two  of  such  pans ;  of  course  one,  or  a 
larger  number  may  be  used,  according  to  requirement.  In 
the  illustration  the  pan  /  on  the  left  is  shown  in  front 
view,  and  the  pan  //  on  the  right,  in  section.  Kv  is  the 
actual  pan  enclosed  by  the  jacket  K.  Steam  circulates  in 
the  space  between  pan  and  jacket,  whereby  the  stock  in  the 
pan  is  heated.  Kv  in  addition,  is  furnished  with  a  steam 
coil  S,  which  may,  however,  be  omitted. 

The  steam  enters  through  the  pipe  Z),  the  space  between 
pan  and  jacket,  passes  into  the  coil  S,  and  escapes  at  b. 
4  * 


50 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


The  water  formed  by  the  condensation  of  steam  in  the  space 
between  pan  and  jacket,  as  well  as  that  which  runs  off  at  b 
from  the  coil  S,  is  carried  away  by  the  pipe  A. 

The  pipe  L  serves  for  conveying  hot  water  to  the  pans, 
and  the  pipe  F  for  the  discharge  of  the  finished  glue  liquor. 
The  stirrer  R,  is  furnished  with  two  paddles,  and  is  set  in 
motion  by  a  transmission  on  the  ceiling  of  the  room.  It 
serves  for  keeping  the  stock  in  the  pans  constantly  agitated, 
solution  being  thus  very  much  promoted. 

FIG.  13. 


The  mode  of  working  with  this  apparatus  is  very  simple. 
Water  being  admitted  into  the  pan  through  L,  the  glue- 
stock  is  introduced  and  the  mass  brought  to  boiling  by  ad- 
mitting steam.  The  finished  glue-liquor  is  from  time  to 
time  drawn  off  through  the  pipe  F  into  the  settling  vessel. 

It  is  generally  preferred  not  to  concentrate  the  glue- 
liquor  in  the  pans  to  such  a  degree  as  required  to  obtain  a 
jelly,  which  after  cooling,  can  be  immediately  moulded, 
experience  having  shown  that  less  concentrated  liquors  can 
be  more  readily  and  better  clarified,  and  yield  a  lighter  and 
more  transparent  glue. 


MANUFACTURE    OF    SKIN    GLUE.  51 

Mr.  Thomas  Lambert  gives  the  following  process  of  cook- 
ing :  The  skins  are  taken  to  the  glue-boiler,  which  is  an 
open  vessel,  8  feet  in  diameter  at  the  top  and  7  feet  deep, 
and  provided  with  a  perforated  false  bottom,  through  the 
center  of  which  passes  a  two-inch  pipe,  one  end  dipping 
below  a  layer  of  water  at  the  bottom,  the  other  projecting 
about  half  the  height  of  the  boiler,  this  part  being  covered 
with  a  perforated  hood  to  spray  the  liquor  through  the 
mass.  The  skins  are  placed  on  the  false  bottom  and  the 
added  water  at  the  bottom  of  the  boiler  is  brought  to  the 
boil  by  means  of  a  steam  pipe.  The  steam  not  being  able 
to  escape  quickly  through  the  dense  mass  of  glue-stock 
above,  exerts  a  pressure  on  the  water,  forces  it  through  the 
pipe,  to  be  sprayed  through  the  mass,  and  ultimately  works 
its  way  to  the  bottom  of  the  boiler  to  be  forced  up  again. 
This  continual  circulation  of  the  hot  liquor  rapidly  dissolves 
the  gelatinous  matter,  and  when  a  strength  of  18  per  cent, 
dry  glue  is  reached,  the  first  run  is  made  to  the  evaporating 
pan,  the  liquor  passing  through  a  filter  of  fine  shavings,  to 
remove  any  suspended  matter.  Fresh  water  is  added  to  the 
boiler,  and  the  boiling  renewed.  Three  extractions  are 
usually  made,  the  last  being  used  for  size. 

In  order  to  avoid  annoyance  to  the  neighborhood  from 
foul  odors,  Terne's  glue-boiler  shown  in  Fig.  14  may  be 
recommended.  The  lead-lined  iron  boiler  A,  with  man- 
holes B  and  C\  on  top  and  side,  is  furnished  with  a  false 
perforated  bottom  upon  which  the  glue-stock  is  placed. 
Underneath  the  false  bottom  lies  the  coil  E  with  valve-box 
e.  The  boiler  is  filled  through  the  upper  man-hole  with 
glue-stock  and  water  admitted,  steam  being  at  the  same 
time  introduced  in  the  coil  and  in  order  to  quickly  heat  the 
water,  direct  steam  is  also  admitted  to  the  boiler  through 
the  pipe  Fand  cock  G.  When  the  water  is  boiling  the 
cocks  G  and  .Fare  closed,  the  coil  furnishing  now  sufficient 
heat.  During  boiling  some  steam  is  allowed  to  escape 
through  the  partly-opened  cock  L,  all  badly-smelling  gases 


52 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


being  thereby  carried  to  the  fire-box  of  a  boiler  where  they 
are  burned.  When  boiling  is  finished,  the  glue  liquor 
remains  for  a  short  time  in  the  boiler  to  allow  the  melted  fat 
to  separate  on  the  surface,  the  cocks  K1  and  K5  serving  for 

FIG.  14. 


drawing  off  the  fat.  The  insoluble  residues  of  the  glue- 
stock  remain  upon  the  false  bottom  and  are  taken  out 
through  the  man-hole  C. 

2.    CLARIFYING    THE    GLUE-LIQUOR. 

The  clearness  of  glue,  i.  e.,  its  freedom  from  undissolved 
substances,  is  by  no  means  a  criterion  of  its  -value  as  an 
agglutinant,  since  pulverulent  inorganic  substances  (white 
lead)  are  frequently  intentionally  introduced  into  some 
varieties,  for  instance  into  Russian  glue,  without  injury  to 


MANUFACTURE    OF    SKIN    GLUE.  53 

their  adhesive  power.  But  as  a  turbid  appearance  may 
also  be  an  indication  of  unsoundness  and  decomposition, 
the  manufacturer  endeavors  by  all  means  to  obtain  a  clear 
product. 

A  strict  distinction  should  be  made  between  clearness  and 
color.  Very  dark-colored  glue  may  be  very  clear,  and  a 
very  pale  variety  the  reverse,  yet  both  possess  excellent 
qualities.  Both  properties,  clearness  and  light  color,  can- 
not be  obtained  by  the  same  process. 

Clearness  will  be  first  referred  to.  If  the  glue-stock  has 
been  properly  prepared  by  rendering  adhering  particles  of 
blood  and  fat  innoxious  by  liming  and  subsequent  careful 
washing,  the  separation  of  the  few  remaining  impurities, 
which  may  have  passed  through  the  straw  filter,  is  readily 
effected  by  allowing  the  liquor  to  stand,  care  being  had  to 
keep  it  liquid  as  long  as  possible  to  give  the  grease  time  to 
rise  and  the  flocculent  and  fibrous  impurities  to  settle. 
This  is  best  effected  in  a  wooden  vat  surrounded  by  a 
wooden  or  sheet-iron  jacket,  the  intermediate  space  between 
jacket  and  vat  being  filled  with  a  non-conductor  of  heat,  or, 
if  required,  it  may  be  heated  by  the  introduction  of  steam. 
The  grease  is  skimmed  off  as  it  rises,  and  when  the  solid 
particles  have  settled  the  liquor  is  drawn  off  through  a  pipe 
placed  a  short  distance  above  the  bottom  of  the  vat. 

The  size  of  the  clarifying  vat  depends  on  the  size  of  the 
boiler.  It  is,  however,  best  to  have  two  vats  for  each 
boiler,  in  order  to  keep  the  first  liquor,  which  is  always 
clearer  and  more  concentrated,  separate  from  the  last  run. 
To  be  able  to  draw  the  upper  layers  of  purer  liquor  into 
cooling  boxes  by  themselves,  the  vats  are  provided  with  fau- 
cets at  different  heights. 

To  prevent  putrefaction  of  the  liquor  which  readily  sets 
in  during  settling  at  a  higher  temperature,  the  vats  should 
be  kept  scrupulously  clean,  and  from  time  to  time  rinsed 
with  clean,  hot  water.  It  is  also  advisable  to  line  them 
with  sheet-iron. 


54  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Should  the  above-described  mechanical  separation  not 
prove  sufficient,  recourse  must  be  had  to  other  means. 
Alum  and  sulphate  of  alumina  have  long  been  used  for 
clarifying,  1  Ib.  of  either  of  them,  pulverized,  added  to 
every  300  gallons  of  liquor,  being  as  a  rule  sufficient. 
Either  of  these  chemicals  removes  the  albuminous  and  ex- 
tractive constituents  of  the  solution,  and  converts  the  dis- 
solved free  lime  into  sulphate  of  lime,  which  settles  readily, 
and  prevents  putrefaction  of  the  glue  solution  while  drying 
under  unfavorable  circumstances.  The  quantity  of  alum 
mentioned  above  does  not  impair  the  quality  of  the  glue. 

Albumen  is  sometimes  used  for  the  better  qualities  of 
glue,  and  generally  for  gelatine,  but  a  cheaper  substitute  is 
fresh  blood,  which  contains  albumen  and  fibrin.  Dry 
albumen  is  dissolved  in  cold  water,  or  white  of  egg  is  used 
direct,  if  procurable.  Before  adding  either  of  these  sub- 
stances, the  liquor  is  cooled  to  130°  F.,  and  the  clarifier 
well  stirred  in ;  then  the  temperature  is  raised  to  about 
200°  F.,  when  coagulation  occurs,  and  the  precipitate  en- 
tangles the  impurities  and  falls  to  the  bottom,  requiring, 
however,  from  twelve  to  twenty-four  hours  to  clear.  It  is 
said  that  glues  clarified  with  albumen  have  a  characteristic 
soapy  smell  and  show  a  tendency  to  foam. 

The  precipitation  of  the  lime  might  be  better  effected  by 
oxalic  acid,  and  the  organic  substances  removed  as  scum  by 
adding  to  the  boiling  mass  some  astringent  matter,  such  as 
a  decoction  of  oak  bark  or  hops ;  but  the  purification  has, 
in  either  case,  to  be  done  at  the  expense  of  glutin. 

A  glue  liquor,  which  does  not  clarify  by  these  means,  is 
not  sound,  and  is  derived  either  from  spoiled  raw  materials, 
or  such  as  have  not  been  thoroughly  prepared,  or  has  been 
injured  in  boiling. 

A  far  more  difficult  matter  than  the  removal  of  mechan- 
ical admixtures  is  to  free  the  liquor  from  the  coloring  sub- 
stances from  which  it  derives  its  color,  and  to  discolor  it 
without  injury  to  the  characteristic  qualities  of  the  glue. 


MANUFACTURE    OF    SKIN    GLUE.  55 

The  use  of  animal  charcoal  for  such  large  quantities  of 
somewhat  thickly-fluid  solutions,  which  are  liable  to  spoil 
at  the  high  temperature  at  which  they  would  have  to  be 
filtered,  is  very  difficult,  and  the  result  not  favorable,  ex- 
cept the  solutions  could  be  successfully  deprived  of  their 
tendency  to  putrefy.  The  use  of  carbolic  acid  is  also  in 
this  case  the  only  means  of  removing  the  great  tendency  of 
the  liquor  to  putrefy,  and  hence,  if  the  liquor  is  to  be  dis- 
colored by  treatment  with  animal  charcoal,  it  can  only  be 
done  without  danger  to  the  glue,  by  mixing  it  with  car- 
bolic acid. 

The  object  is  more  easily  effected  by  bleaching  the  raw 
materials  previous  to  boiling  them  to  glue. 

This  is  accomplished  by  placing  the  glue-stock,  thor- 
oughly limed  and  while  still  moist,  in  a  bath  of  chloride  of 
lime,  not  too  strong,  as  otherwise  the  solution  of  the  mate- 
rials becomes  difficult.  A  bath  of  the  proper  concentration 
is  made  by  dissolving  about  9  ozs.  of  chloride  of  lime  in 
sufficient  water  to  cover  110  Ibs.  of  glue-stock.  After  one 
hour  add  sufficient  hydrochloric  acid  to  obtain  an  acid  re- 
action, which  is  recognized  by  litmus-paper  dipped  in  the 
bath  turning  red. 

Although  the  glue-stock  is  not  bleached  entirely  through 
by  this  process,  the  thin  portions  and  outsides  of  the  thick 
material  acquire  a  lighter  color,  and  the  first  run  of  glue 
solution  will  have  a  light  color  and  can  then  be  treated  fur- 
ther without  much  difficulty. 

Sulphurous  acid  has  been  successfully  used  for  the  pro- 
duction of  colorless  glue  without  the  necessity  of  boiling. 

Waste  of  hides  and  skins  is  the  only  available  material 
for  this  process.  Place  the  waste  in  water  until  putrefac- 
tion sets  in.  When  this  is  the  case  wash  the  material  in  a 
bag  or  wicker  basket  in  running  water.  Then  pour  2J 
parts  of  sulphurous  acid  over  12  parts  of  wet  material,  mix 
the  whole  thoroughly  and  let  it  stand  in  a  hermetically 
•closed  vessel  for  24  hours.  Now  draw  off  the  acid,  and 


56  GLUE,    GELATINE,    CEMENTS,    PASTES. 

after  washing  the  material  thoroughly  repeat  the  operation. 
When  the  vessel  containing  the  mixture  of  material  and 
sulphurous  acid  is  opened  for  the  second  time  the  foul  odor 
should  be  entirely  superseded  by  that  of  sulphurous  acid, 
this  being  a  sure  indication  of  the  correct  execution  of  the 
process.  Wash  the  material,  and,  after  squeezing,  throw  it 
into  a  vat  large  enough  not  to  be  filled  by  it  more  than 
two-thirds  full.  After  filling  the  vat  with  water  allow  the 
mass  to  digest  at  a  temperature  of  109.4°  F.  for  24  hours. 
The  result  will  be  a  gelatinous  solution,  which  is  drawn  off 
and  converted  into  glue.  The  undissolved  residue  is  trans- 
formed into  gelatinous  solution  by  pouring  water  over  it 
and  allowing  it  to  stand  at  a  somewhat  higher  temperature. 

For  carrying  out  this  process  and  that  of  bleaching  with 
chloride  of  lime  it  is  best  to  use  a  vat  provided  with  a  stir- 
ring apparatus,  somewhat  like  a  hollander  used  by  paper- 
makers,  as  being  most  suitable  for  washing,  disintegrating 
and  mixing  the  material. 

Glue-liquor  may  also  be  successfully  bleached  with  sul- 
phurous acid,  and  in  speaking  later  on  of  the  manufacture 
of  bone  glue,  a  very  practical  apparatus  for  this  purpose 
will  be  described. 

Glue-liquor  bleached  by  sulphurous  acid  clarifies  very 
readily  and  is  protected  from  spoiling.  The  resulting  glue 
remains,  however,  quite  acid,  and  cannot  be  used  for  all 
purposes,  especially  not  in  combination  with  colors,  chem- 
icals, etc.,  upon  which  the  acid  has  a  destructive  effect. 

3.  FORMING  OR  MOULDING  THE  GLUE. 

After  clarifying,  the  liquor  is  run  into  moulds  of  deal 
wood  or  sheet  iron,  lightly  joined  and  of  a  rectangular  form, 
slightly  converging  towards  the  bottom  so  as  to  allow  the 
more  ready  detachment  of  their  contents.  They  are  about 
3.25  feet  long,  10  inches  wide  at  the  top,  and  7f  inches  at 
the  bottom,  and  5  inches  deep.  When  very  regular  cakes 
of  glue  are  desired,  cross  grooves  of  the  required  shape 


MANUFACTURE    OF    SKIN    GLUE.  57 

cut  in  the  bottoms.  After  being  well  cleansed  and  ranged 
upon  a  level  the  boxes  are  filled  to  the  brim  through  large 
funnels  with  strainer  cloths  affixed  to  their  barrels.  It  is 
best  to  place  them  upon  perfectly  clean  stone  flagging 
slightly  inclined  towards  a  reservoir  for  the  reception  ot 
such  portions  of  their  contents  as  may  run  over.  The 
apartment  in  which  the  work  is  performed  should  be  clean 
and  airy,  a  dry  cellar  being  the  best  for  the  purpose.  In 
place  of  a  large  number  of  boxes,  a  shallow  vessel  lined 
with  sheet-iron  and  capable  of  holding  the  entire  quantity 
of  liquor  is  sometimes  used,  from  which  the  solid  jelly  is 
cut  out  in  cubic  masses,  which  are  further  divided. 

This  arrangement  can  only  be  recommended  for  estab- 
lishments where  but  one  variety  of  glue  is  produced,  and 
the  different  layers  in  the  clarifying  vat  are  not  separated 
according  to  their  clearness.  Before  running  the  liquor 
into  the  boxes  the  latter  should  be  moistened  with  water, 
or,  if  made  of  wood,  coated  with  oil,  stearine,  or  paraffin  to 
prevent  the  liquor  from  penetrating  the  wood  and  the 
solidifying  glue  from  adhering  to  the  sides. 

After  the  solidification  of  the  glue,  which  generally  takes 
place  in  twelve  to  eighteen  hours,  the  boxes  are  inverted 
upon  a  table  with  a  smooth  top  of  wood  or  stone  previously 
wetted,  so  as  to  prevent  the  adherence  of  the  gelatinous 
cake  to  its  surface.  To  detach  it  from  the  sides  of  the 
boxes  the  moistened  blade  of  a  large  knife  is  generally 
used. 

Cutting  the  cubes  of  glue  into  commercial  cakes  or 
sheets  is  readily  accomplished  by  observing  the  following 
instructions : — 

The  shape  of  the  cakes  depends  principally  on  custom. 
The  consumer  is  used  to  a  certain  variety  of  glue,  and  if  it 
is  not  offered  to  him  in  the  customary  shape,  he  might 
refuse  it  and  take  his  custom  elsewhere.  The  quality  of 
the  glue  is  the  next  point  to  be  considered.  If  very  dark, 
it  is  advisable  to  cut  the  glue  into  thin  cakes,  and  if 


58  GLUE,    GELATINE,    CEMENTS,    PASTES. 

turbid,  into  thick  ones,  in  order  to  make  this  defect  the 
less  apparent.  Thicker  cakes  can  also  be  cut  if  the  condi- 
tions for  drying  them  are  favorable,  and  thinner  ones  if  the 
reverse  is  the  case. 

The  mass  is  first  divided  b}7  a  steel  or  brass  wire  stretched 
over  a  frame,  like  a  bow  saw,  into  horizontal  layers.  The 
size  of  these  layers  is  regulated  by  guides  which  are  placed 
at  distances  corresponding  with  the  desired  thickness  of  the 
cake  of  glue.  Instead  of  one  wire,  as  many  as  the  cakes 
of  glue  to  be  cut,  can  be  stretched  over  the  frame,  which 
is  best  made  of  iron  and  provided  with  conical  pins  by 
means  of  which  the  wires  can  be  tightened,  in  the  same 
manner  as  piano  strings,  when  they  have  become  slack  by 
use. 

The  width  and  thickness  of  the  cakes  of  glue  are  regu- 
lated by  the  distance  of  the  wires  from  each  other,  and  the 
length  by  the  width  of  the  box.  The  cakes  thus  formed 
are  dexterously  lifted  from  the  block  with  the  moist  blade 
of  a  large  knife  and  placed  upon  nets. 

Instead  of  using  wooden  or  sheet-iron  cooling-boxes,  it  is 
recommended  to  pour  a  layer  of  liquor  of  the  desired  thick- 
ness of  the  glue  cakes  upon  large  polished  stone  slabs,  and 
when  congealed,  cut  it  into  sheets,  which  are  placed  upon 
the  nets  to  dry.  The  advantages  of  this  method  are 
obvious.  The  liquor  cools  more  quickly  by  being  exposed 
in  a  thin  layer  upon  a  large  surface,  which  reduces  the 
danger  of  spoiling,  and  a  strong  evaporation  of  water  and 
consequent  concentration  take  place.  Besides,  the  cakes 
show  the  smooth  surface  of  the  polished  stone,  and  become 
in  a  short  time  so  hard,  that  when  placed  upon  the  nets, 
the  twine  will  make  no  impression  upon  them. 

Liquors  which  in  gelatinizing  do  not  become  very  solid, 
are  not  run  into  forming  boxes,  but  upon  glass  or  zinc 
plates,  and  thus  spread  out  in  a  thin  layer,  acquire  suffi- 
cient solidity  to  be  removed  cake  by  cake  after  being  cut. 
The  plates  upon  which  the  glue  is  run  are  placed  in  frames 


MANUFACTURE    OF    SKIN    GLUE.  59 

and  laid  upon  a  table  furnished  with  a  riin  about  1  inch 
deep.  To  acclerate  gelatinization  of  the  liquor,  the  table 
is  flooded  with  water  before  placing  the  plates  upon  it. 

Where  cooling-boxes  are  used,  the  jelly  when  completely 
congealed  is  placed  upon  a  table  with  a  stone  plate,  by 
inverting  the  boxes,  and  then  cut  into  cakes.  Figs.  15  and 
16  represent  the  tools  for  cutting  the  jelly  into  cakes.  The 
block  of  glue  is  laid  upon  the  surface  A,  Fig.  15,  and  the 
frame,  B,  is  gently  drawn  along  in  the  grooves,  a.  In  the 

FIG.  15. 


upright  portion  of  the  frame  are  fixed  wires  at  such  a  dis- 
tance from  each  other  as  required  for  the  thickness  of  the 
cakes  to  be  cut. 

When  the  block  of  glue  has  been  cut  in  this  direction,  it 
is  divided  by  cuts  perpendicular  to  the  former,  into  cakes 
of  a  size  in  which  the  finished  product  is  to  be  brought  into 
commerce.  The  apparatus  shown  in  Fig.  16  serves  for  this 

FIG.  16. 


purpose.  The  vertical  bars,  a,  furnished  with  the  wire, 
b  b,  serve  as  guides.  The  sheets  thus  formed  are  lifted  from 
the  block  with  the  moist  blade  of  a  large  knife,  and  laid 
upon  nets. 


60 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


The  machine  shown  in  Figs.  17  and  18  is  the  invention 
of  Mr.  J.  Schneible,  and  it  is  for  slicing  and  spreading  glue- 
jelly  preparatory  to  drying,  and  it  consists  in  the  combina- 
tion of  a  reciprocating  cutter  with  the  jelly-box  and  a  trav- 
eling belt-carrying  frame  for  receiving  the  slices  as  cut  by 
the  knife. 

Fig.  17  is  a  partly  sectional  side  view  of  the  machine, 
and  Fig.  18  is  a  cross-section  of  the  same. 

A  A  are  side  bars  of  the  supporting  frame,  fitted  at  the 

FIG.  17. 


ends  with  cross-shafts,  a',  carrying  pulleys,  a  a,  around  which 
are  endless  belts,  b  b.  c  c  are  slide-ways  upon  the  bars,  A, 
and  d  d  are  slides  carrying  a  cross-plate,  e,  and  also  a  plate,/, 
to  which  plate  e  is  attached  a  knife  or  cutter,  g,  the  cutting 
edge  of  which  is  at  the  edge  of  the  plate,  /,  and  about  the 
same  thickness  as  the  slices  to  be  cut.  The  cross-shaft,  h, 

FIG.  18. 


is  fitted  in  boxes  on  bars,  A,  and  near  one  end  thereof  it  is 
provided  with  cranks  at  its  ends,  which  connect  by  rods,  i, 
to  the  slides,  d. 

From  the  opposite  ends  of  the  slides,  rods,  k,  pass  to  loose 
arms,  I,  on  the  shaft  at  the  opposite  end  of  the  machine,  and 
the  arms,  I,  carry  pawls,  V ,  that  engage  ratchet-wheels,  m, 
fixed  on  the  shaft,  so  that  the  shaft,  h,  being  revolved,  the 


MANUFACTURE    OF    SKIN    GLUE.  61 

slides,  with  plates,  e  f,  are  reciprocated,  and  at  the  back- 
ward movement  of  the  cutter  the  pawls  engage  the  ratchet- 
wheels,  and  belts,  6,  are  moved  a  distance  equal  to  the 
movement  of  the  knife. 

The  jelly-box,  n,  is  fixed  to  side  bars,  A,  by  brackets  at 
its  ends,  as  shown  in  Fig.  18,  and  is  placed  above  the  cutter 
and  the  plate,  e,  so  that  when  the  plate,  /,  is  drawn  out  from 
beneath  the  box  the  plate,  e,  takes  its  place  for  holding  up 
the  block  of  jelly. 

In  operation  the  block  of  jelly  is  placed  in  box  n,  resting 
on  plate  e.  A  frame  provided  with  netting — such  as  is  used 
for  drying  glue — is  placed  on  belts,  6,  beneath  the  box,  and 
the  shaft,  h,  being  rotated  by  power,  the  cutter  moves  for- 
ward and  cuts  a  slice  from  the  jelly.  The  plate,  /,  at  the 
same  time  moving  away,  the  slice  passes  upon  the  frame, 
and  the  return  movement  taking  place,  plate  /  is  carried 
beneath  the  jelly-block,  and  the  belts  being  at  the  same 
time  moved,  the  frame  is  carried  forward  in  position  for  re- 
ceiving the  next  slice  apart  from  the  first  one.  In  this 
manner,  as  slice  after  slice  is  cut,  they  are  spread  on  the 
frame,  and  the  frames,  when  filled,  are  carried  to  the  end  of 
the  machine  for  removal.  The  plate,  /,  is  adjustable,  so  as 
to  vary  the  thickness  of  the  slices  cut. 

The  box  may  be  divided  into  cells  of  any  size  desired,  so 
that  each  movement  of  the  knife  will  cut  a  slice  from  the 
bottom  of  each  cell,  and  the  box  extending  the  full  width 
of  the  drying  frames,  all  the  slices  cut  at  once  will  be 
properly  spread. 

In  order  to  keep  the  plates,  e  /,  moist,  so  as  to  prevent 
the  glue-jelly  from  sticking  thereto,  there  are  fitted  at  the 
sides  of  the  jelly-box,  n,  open-bottomed  boxes,  o,  containing 
fibrous  material  soaked  with  water,  which,  resting  on  plates, 
efj  keeps  their  surfaces  moist. 

The  machine  saves  the  troublesome  and  expensive  work 
of  spreading  the  jelly  by  hand,  as  has  been  heretofore 
practiced. 


62 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


The  knife  is  to  be  attached  to  plate,  e,  in  any  suitable 
manner,  and  the  surface  of  plate,  /,  rnay  be  corrugated,  so- 
as  to  slide  on  the  jelly  more  readily. 


FIG.  19. 


The  cutting  apparatus  patented  by  M.  Devoulx,  of  Mar- 
seilles, is  much  used  in  France.  The  machine  stands  upon 
a  board  or  table,  upon  which  are  fastened  two  uprights, 
far  enough  apart  to  allow  of  the  passage  of  a  truck  carrying 
the  glue,  which  is  cut  into  cakes  by  blades  or  wires  stretched 
between  the  uprights. 


Fig.  19  shows  the  perspective  elevation  of  the  machine 
with  its  truck.  The  upper  part  is  filled  up  for  the  recep- 
tion of  the  glue  to  be  cut  up  into  cakes.  The  sides  are 


MANUFACTURE    OF    SKIN    GLUE.  63 

omitted  in  this  figure  in  order  to  admit  of  a  better  explana- 
tion of  the  separate  parts. 

Fig.  20  gives  the  same  view,  except  that  the  truck, 
the  upper  part  of  which  is  closed,  is  between  the  uprights, 
and  contains  the  glue  to  be  cut. 

Fig.  21  represents  the  moment  the  wires  have  passed 
through  the  glue  and  cut  it  into  cakes.  In  all  the  figures,  a 
is  the  wooden  frame  upon  which  the  machine  rests,  b  the 

Fig.  21. 


table-plate  fastened  to  the  frame,  c  and  d  are  the  uprights, 
between  which  the  cutting  wires  are  stretched,  and  /  the 
truck  carrying  the  glue. 

Figs.  22  and  23  show  the  truck  by  itself,  g  representing 
the  bottom,  and  h  the  back,  which  is  provided  with  slight 


grooves,  into  which  the  wires  catch  to  assure  the  entire  cut- 
ting through  of  the  block  of  jelly  ;  i  is  the  upper  part  of  the 
truck,  which  opens  by  means  of  a  hinge,  and  when  closed 
is  fastened  with  the  pin,  k.  This  upper  part  of  the  truck 
is  fastened  to  the  back  part  of  the  truck  by  means  of  a 


64  GLUE,    GELATINE,    CEMENTS,    PASTES. 

screw,  which  allows  it  to  be  set  higher  or  lower,  according 
to  the  size  of  the  block  of  jelly  to  be  cut;  m  is  the  bar  of  a 
rack  fastened  to  the  truck,  and  serves  for  moving  the  latter. 


The  driving  gear,  n,  the  shaft  of  which  carries  a  crank,  o, 
catches  into  the  rack. 

Two  boards,  one  on  each  side  of  the  truck,  serve  to  keep 
the  block  of  jelly  in  position,  and  guide  the  truck. 

With  this  machine  120,000  to  130,000  cakes  can  be  cut 
in  five  or  six  hours. 

3.  DKYING  THE  CAKES  OF  GLUE. 

Drying  the  cakes  is  without  doubt  the  most  precarious 
part  of  the  manufacture.  The  jelly  contains  a  large  quan- 
tity of  water  which,  to  prevent  decomposition  of  the  jelly 
before  it  is  converted  into  glue,  must  be  evaporated  as 
quickly  as  possible.  In  favorable  weather,  drying  may  be 
accomplished  either  in  the  open  air  or  in  covered  sheds. 

Drying  in  the  open  air  is  connected  with  many  incon- 
veniences, for  if  the  sun  strikes  the  cakes  of  jelly  when  they 
still  contain  a  large  quantity  of  water,  they  may  become 
soft  so  as  to  run  through  the  meshes  of  the  net,  or  they  may 
dry  so  quickly  as  to  prevent  them  from  contracting  to  their 
proper  size  without  numerous  cracks  and  fissures.  If  frost 
supervenes,  numerous  cracks  may  be  formed  in  the  cakes 
from  the  congelation  of  their  water,  or  a  shower  of  rain  may 
cause  much  work  and  damage.  In  consideration  of  all 
these  inconveniences,  it  is  best  to  conduct  the  operation  in 
a  drying-room. 

To  insure  a  constant  circulation  of  air,  which  is  abso- 


MANUFACTURE    OF    SKIN    GLUE.  65 

lutely  necessary  for  the  expulsion  of  the  aqueous  vapor 
•caused  by  the  evaporation  of  such  a  large  quantity  of  water, 
the  drying-room  should  be  at  least  10  feet  high,  even  if  in- 
tended for  summer  use  only,  and  the  windows  be  provided 
with  Venetian  blinds  so  as  to  shut  out  the  sun,  if  necessary, 
without  disturbing  the  circulation  of  air. 

To  dry  the  cakes  in  heated  rooms  in  winter  is  a  more 
difficult  matter,  as  provision  has  to  be  made  for  the  removal 
of  the  aqueous  vapor,  and  a  current  of  warm  dry  air  has  to 
be  kept  up  at  the  same  time.  But  such  a  room  is  an  absolute 
necessity  for  the  manufacturer  on  a  large  scale,  who,  in  order 
to  carry  on  his  business  without  interruption  throughout 
the  entire  year,  must  be  independent  of  the  changes  of  wind 
and  weather. 

The  size  of  the  drying-room  should  be  proportional  to 
the  daily  production.  Constructions  are  fitted  up  with  the 
requisite  frames  for  the  reception  of  the  glue  cakes,  and  are 
heated  by  steam  pipes  arranged  along  the  walls.  In  the 
floor  in  the  immediate  neighborhood  of  the  steam  pipes  are 
openings,  which  can  be  opened  and  shut  at  pleasure,  for  the 
admission  of  fresh  dry  air.  The  latter  on  entering  the 
room  is  heated,  and  after  passing  over  the  frames  and  ab- 
sorbing water  from  the  glue  cakes,  escapes  through  openings 
in  the  ceiling  to  a  space  above  it  from  which  it  is  with- 
drawn by  means  of  ventilators  in  the  roof.  A  constant 
change  of  air  must  be  kept  up.  The  quick  drying  of  the 

FIG.  24. 


glue  is  of  the  utmost  importance,  as  otherwise  the  jelly 
putrefies  either  entirely  or  partially,  and  the  glue  acquires 
a  turbid  and  mean  appearance.  Too  much  heat  causes  the 
cakes  to  bend  and  crack.  The  cakes  are  laid  upon  wide- 
5 


66 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


meshed  nets  of  twine  stretched  in  frames  6  J  to  8  feet  long 
and  3J  feet  wide.  Fig.  24  represents  the  form  of  nets 
commonly  used.  The  nets  are  placed  upon  frames,  such  as 
shown  in  Fig.  25,  arranged  around  the  drying-room  in  the 


neighborhood  of  the  steam  pipes  and  air  flues.  As  the 
cakes  have  to  be  occasionally  turned  upside  down  upon  the 
nets,  the  latter  must  be  placed  at  convenient  distances,  one 
above  the  other  in  the  frames. 

The  use  of  twine  netting  has  been  found  to  be  attended 
with  many  disadvantages,  the  principal  ones  of  which  are 
given  by  S.  Rideal  as  follows : 

1.  "  Being  freely  handled  in  the  making,  the  netting  is 
almost    always    impregnated    with    dangerous    organisms 
which  penetrate  the  moist  glue  cakes,  and  cause  moulding 
or  putrefaction.     When  this  occurs,  it  is  usually  attributed 
to  a  state  of  the  atmosphere,  but  if  the  cakes  are  examined, 
the  alteration  will  generally  be  found  to  originate  along  the 
lines  made  by  the  netting.     The  fault  could  be  cured  by 
sterilizing  the  net  for  an  hour  at  212°  to  248°  F.  in  a  hot 
oven,  but  besides  the  expense,  the  fibre  is  thereby  weak- 
ened.    Moreover,  the  spores  of  a   few   bacteria,    such    as 
Bacillus  subtilis,  which  is  widely  distributed  and  has  the 
power  of  liquefying  gelatine,  will  bear  a  heat  of  248°  F.  for 
over  an  hour,  and  still  be  capable  of  growing. 

2.  "  However  smooth  the  fibre,  the   glue  will  stick  in 
places,  leaving  small  remains,  which  being  hygroscopic, 


MANUFACTURE    OF    SKIN    GLUE.  67 

become  '  sour,'  and  set  up  the  objectionable  bacterial  changes 
in  the  subsequent  batches. 

3.  "  Owing  to  sagging,  rotting,  scouring,  or  wearing  into 
holes,  the  life  of  cotton  or  hemp  netting  is  so  short  that  the 
constant  renewal  is  a  considerable  item.     A  whole  batch  is 
frequently  spoilt  by  the  fault  of  a  net.     In  some  works, 
heaps  of  old  netting  are  found,  which  become  very  putrid 
in  the  rain  and  sun,  and  give  rise  to  mysterious  bacterial 
inroads  in  the  factory.     In  others  they  are  regularly  burnt 
under  the  boilers. 

4.  "  The  considerable  overlap  or  selvedge  required  for 
securing  the  edges  of  the  net  involves  a  waste  of  the  area, 
and  also  some  difficulty  in  refixing." 

For  this  reason  metallic  netting  has  been  largely  adopted. 
The  best  material  has  proved  to  be  a  heavily  galvanized 
iron-wire  netting  having  no  less  than  15  to  25  per  cent,  of 
its  weight  of  zinc.  It  can  be  strengthened  by  longitudinal 
and  transverse  wires  or  ribs.  It  must  be  examined  by  the 
microscope  to  see  that  it  is  perfectly  free  from  holes  or 
cracks,  and  should  last  at  least  two  years  in  constant  use. 

The  temperature  of  the  drying-room  requires  careful  reg- 
ulation, and  should  never  be  allowed  to  rise  above  68°  to 
77°  F.,  as  otherwise  the  glue  would  soften  and  run  through 
the  meshes  of  the  net.  or  adhere  so  firmly  to  the  twine  as  to 
require  the  nets  to  be  put  in  hot  water  for  its  separation. 
Dry  ness  of  air  is  of  far  greater  importance  in  the  drying 
process  than  a  high  temperature.  To  promote  this  dryness 
of  air  and  prevent  the  aqueous  vapor  from  condensing, 
evaporating,  and  again  condensing  upon  the  cold  walls  of 
the  room,  they  are  wainscoted.  Thus  protected  by  a  bad 
conductor,  they  acquire  a  higher  temperature,  and  the 
aqueous  vapor,  instead  of  being  precipitated  upon  them,  is 
carried  off  by  the  air-currents. 

As  the  cakes  placed  in  the  immediate  neighborhood  of 
the  steam  pipes  and  near  the  floor  where  the  dry  air  enters, 
dry  quickest,  the  nets  containing  them  are  shifted  after 


68  GLUE,    GELATINE,    CEMENTS,    PASTES. 

some  time  to  a  higher  part  of  the  drying-room  and  their 
former  places  filled  with  cakes  still  wet.  When  the  cakes 
are  dry,  they  are  finally  desiccated  in  a  room  at  a  higher 
temperature,  which  serves  to  harden  and  improve  them. 

In  modern  times  drying-rooms  have  been  almost  entirely 
abandoned  and  in  this  country  long  drying  galleries  are 
used,  sometimes  250  feet  in  length  and  6  to  8  feet  square, 
with  traveling  platforms  on  rails  carrying  the  sheets  of  glue 
on  stout  galvanized  netting.  Wood  is  found  to  be  a  better 
material  for  the  galleries  than  stone  or  brick. 

Figs.  26  to  28  show  an  apparatus  for  drying  glue  which 
is  the  invention  of  W.  A.  Hoeveller. 

Fig.  26  is  a  plan  section,  and  Fig.  27  a  side  elevation  in 
section,  of  this  improved  drying-alley.  Fig.  28  is  an  end 
view  in  section. 

The  form  and  arrangement  are  as  follows  : — 
A  B  represent  the  two  parts  of  the  alley,  separated  by  the 
partition  C,  which  is  shorter  than  the  alley,  so  as  to  leave 
a  communicating  space  at  both  ends. 

At  the  front  of  section  A,  is  located  a  blower,  Z>,  actuated 
by  a  steam-engine  or  other  motor,  E,  also  located  within 
the  walls  of  the  alley.  The  whole  current  from  blower  D, 
is  directed  through  section  A  of  the  alley,  whence  it  turns 
into  section  B,  and  comes  back  through  it,  to  be  again 
drawn  into  and  forced  out  of  the  blower  into  section  A. 
By  this  means  the  contained  air  of  the  alley  is  set  in  con- 
tinuous motion  through  the  two  sections  successively,  and 
as  the  structure  is  made  as  air-tight  as  practicable  in  such 
cases,  the  air  remains  unchanged  until  the  doors  F,  or  either 
of  them,  are  opened  to  discharge  the  vitiated  air  and  let  in 
the  fresh. 

In  sections  A  and  B,  is  placed  the  railway  a  a,  to  admit 
of  the  convenient  movement  of  the  contents  in  process  of 
drying,  which  are  generally  set  on  cars  or  buggies. 

In  section  A,  in  front  of  blower  D,  is  placed  a  steam  or 
other  heating  device,  G,  which  may  be  of  any  form  or 


MANUFACTURE    OF    SKIN    GLUE. 


69 


design  adapted  to  allow  the  air  from  blower  D  to  pass 
through  it  and  to  heat  such  air  while  passing  therethrough. 
The  inventor  prefers  the  radiating  coil  for  such  purpose, 
the  steam  entering  at  6,  and  emerging  at  c.  At  the  other 
end  of  the  alley,  which  by  the  double  construction  is  in 
section  B,  just  back  of  the  blower  and  heating-coil,  there  is 
placed  a  condensing-coil,  H,  of  a  construction  similar  to  coil 

FIG.  26. 


FIG.  27. 


FIG.  28. 


G,  and  having  inlet  d,  and  outlet  e.  Through  this  con- 
denser there  is  kept  flowing  a  refrigerating  liquid  or  brine, 
which  renders  the  condenser  very  cold.  The  continuous 
current  of  air  from  the  blower  passes  over  the  contents  of 
the  cars  or  trays  in  the  alley  and  takes  up  moisture  in  its 
passage.  After  such  passage  the  air  is  charged  with  moist- 
ure and  comes  in  contact  with  the  coils  of  the  condenser  H, 


70 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


upon  which  the  charge  of  moisture  is  condensed,  and  the 
air  emerges  dry  again,  enters  the  blower,  and  is  again  made 
the  vehicle  by  which  the  moisture  of  the  glue  or  other  con- 
tents is  transported  to  and  deposited  on  the  condenser. 

In  drying  glue  by  this  method  do  not  use  the  steam-coil 
at  the  first  stage  of  drying  a  charge,  as  the  drying  should 
not  be  effected  too  rapidly  ;  but  as  soon  as  the  product 
begins  to  stiffen  properly,  admit  the  steam  to  the  coil  G, 
and  thereafter  the  operation  is  continuous,  as  above  de- 
scribed. 

By  doubling  up  the  alley  into  two  sections,  as  shown,  the 
inventor  is  enabled  to  erect  the  alley  in  a  more  contracted 
space.  In  a  length  of  ninety  feet  he  obtains  the  benefit  of 
a  single  alley  one  hundred  and  eighty  feet  long.  Section 
B  may,  if  desired,  be  located  on  top  of  section  A.  Doors 
may  be  located  wherever  desired,  to  facilitate  the  movement 
of  the  trays  or  cars  and  the  placing  of  them  in  and  their 
removal  from  the  alley. 

By  the  above  apparatus  the  drying  can  be  perfected  in  a 
very  much  shorter  time  than  can  be  done  by  the  old  alleys, 

FIG.  29. 


144 


and  operations  can  be  conducted  in  hot  weather  without 
hindrance  from  the  condition  of  the  atmosphere. 

In  cases  where  the  atmosphere  is  dry  enough  to  dispense 
with  the  heater  and  the  condenser,  the  inventor  can  throw 
the  doors  F  wide  open,  extend  the  partition  C  out  to  that 
end  of  the  alley,  and  then  preserve  a  continuous  forced  draft 
of  sufficiently  dry  air  in  both  alleys  for  the  purpose.  As 


MANUFACTURE    OF    SKIN    GLUE. 


71 


there  are  many  days  during  the  year  fine  enough  to  give 
reasonably  dry  air,  operations  can  be  conducted  with  the 
blower  alone  in  this  way,  and  thus  economize  the  steam  and 
the  refrigerating-brine. 

Figs.  29  and  30  show  a  longitudinal  section,  with  upper 
and  ground  floor  plans  of  a  modern  drying-house,  as  given 
by  Thomas  Lambert.  In  the  ground  floor  the  whole  of  the 
liquors  are  jellied  in  coolers,  and  then  cut  into  cakes  by 
the  two  cutting  machines  in  the  centre.  Here  a  hoist,  E, 
Fig.  30,  is  placed  which  carries  the  cut  cakes  on  "  glasses  " 

FIG.  30. 


$ 


to  the  floor  above.  This  forms  the  drying-floor,  and  is  par- 
titioned off"  in  three  divisions,  running  nearly  the  length  of 
the  building.  The  two  outer  divisions  form  the  tunnels 
proper,  and  at  the  ends  are  fixed  two  powerful  revolving 
fans,  driven  at  high  speed  and  drawing  the  air  through  the 
tunnels  at  a  high  rate.  At  the  opposite  ends  of  the  fans 
are  fixed  a  series  of  6-inch  pipes,  heated  up  by  waste  steam, 
and  the  air  passing  between  is  warmed  up  to  any  desired 
temperature,  of  necessity  below  78°  F.  In  the  center  pass- 


72  GLUE,    GELATINE,    CEMENTS,    PASTES. 

age  a  number  of  girls  are  employed  in  transferring  the  cut 
cakes  to  the  nets,  which  are  built  upon  a  carriage  running 
on  a  small  railway.  The  carriage  with  the  complement 
of  filled  nets  is  run  to  the  end  of  the  division,  transferred  to 
the  lower  railway,  C,  by  which  it  is  carried  either  to  the 
right  or  left  hand  tunnels  as  desired ;  the  glue  when  dried 
on  the  nets  is  run  to  the  other  end  and  by  another  lower 
railway  brought  to  the  middle  division,  and  ultimately  by 
the  hoist  raised  to  a  large  store-room,  seen  in  section,  where 
the  glue  is  sorted  and  bagged.  At  the  end  of  the  store- 
room is  placed  a  grinding  machine,  and  all  the  off-color  and 
twisted  cakes  are  ground  to  a  powder  and  sold  as  powdered 
glue.  T^he  manufacturer  by  varying  the  size  of  the  cake,  its 
thickness,  and  its  color,  may  make  any  number  of  grades 
from  the  same  boiling. 

Fleck  proposes  to  accelerate  the  drying  of  glue  by  utiliz- 
ing the  water-absorbing  power  of  some  salts,  such  as  Epsom 
and  Glauber's  salts,  ammonium  sulphate,  crystallized  acid 
sodium  sulphate,  etc.,  for  the  purpose  of  withdrawing  water 
from  the  glue  cakes.  For  the  practical  application  of  this 
principal  a  shallow,  watertight,  wooden  box  is  required. 
The  bottom  of  the  box  is  sprinkled  with  a  layer  of  the 
water-absorbing  salt  about  half  an  inch  deep,  and  covered 
with  a  moist  linen  cloth.  Upon  this  is  placed  the  jelly  cut 
into  sheets  and  also  covered  with  a  moist  cloth,  a  layer  of 
salt  being  finally  scattered  over  it.  After  standing  for  a 
few  hours,  the  box  is  slightly  inclined  and  the  salt  solution 
allowed  to  drain  off  through  a  hole  in  the  bottom,  the 
dropping  ceasing  in  from  12  to  18  hours.  If  now  the  upper 
cloth  is  taken  off  with  its  layer  of  salt,  the  glue  beneath  it 
will  be  found  so  far  deprived  of  its  moisture  that  when  placed 
in  the  sun  or  exposed  to  other  heat,  it  will  become  com- 
pletely dry  in  a  short  time  without  either  melting  or  spoil- 
ing, and  in  winter  may  be  laid  upon  drying-floors  with  the 
same  result.  The  salt-solution  formed  may  be  evaporated 
to  crystallization  and  the  salt  thus  obtained  be  again  used. 


MANUFACTURE    OF    SKIN    GLUE.  73 

After  the  treatment  with  the  salt,  the  jelly  contains  70 
to  75  per  cent,  of  anhydrous  glue,  while  the  content  in  jelly 
not  thus  treated  varies  between  7  and  28  per  cent,  accord- 
ing to  the  concentration  of  the  liquor  from  which  it  has 
been  derived.  It  is  claimed  that  the  adhesive  power  of  the 
glue  is  not  injured  by  this  treatment. 

Commercial  glue  must  not  only  be  thoroughly  dry,  but 
should  also  present  a  good  appearance,  showing  especially 
lustre.  However,  after  drying,  the  glue  is  dull,  spotted, 
dusty  and  sometimes  even  mouldy.  To  give  a  good  lustrous 
appearance  the  dry  cakes  are  dipped  in  warm  water  and 
replaced  upon  the  nets  to  dry. 


CHAPTER  V. 

MANUFACTURE  OF  BONE-GLUE. 

THE  manufacture  of  bone-glue  differs  chiefly  from  that  of 
skin-glue  in  the  processes  employed  for  the  conversion  of 
the  glue-yielding  tissues.  This  conversion  may  be  effected 
by  boiling  the  bones  with  water,  or  subjecting  them  to  the 
action  of  steam,  or  by  first  extracting  their  mineral  consti- 
tuents with  acid,  and  boiling  the  remaining  cartilaginous 
mass  with  water  until  dissolved. 

When  the  finest  quality  of  all  varieties  of  glue,  namely, 
colorless  gelatine,  is  to  be  manufactured,  the  bones  should 
not  be  comminuted  in  a  stamping  mill,  because  in  conse- 
quence of  the  unavoidable  development  of  heat,  they  acquire 
a  slightly  empyreumatic  odor  which  adheres  to  the  gelatine 
prepared  from  them,  and  cannot  be  removed. 

In  factories  working  on  a  small  scale,  the  bones  are  com- 
minuted by  hand,  being  placed  upon  a  grate-like  support 
of  heavy  iron  rods  and  crushed  with  a  wooden  hammer,  the 
face  of  which  is  studded  with  big-headed  nails.  In  larger 
establishments  the  crushing  rolls  previously  described  are 
used,  and  in  order  to  lessen  the  effect  of  heating  as  much  as 
possible,  the  crushed  bones  are  allowed  to  fall  directly  into 
a  vessel  filled  with  water. 

Fat  being  a  very  valuable  constituent  of  bones,  it  should 
be  gained  as  completely  as  possible,  by  boiling  or  steaming 
the  bones,  or  by  extracting  them  by  means  of  a  solvent, 
such  as  benzine  or  carbon  disulphide. 

1.    BOILING  BONES. 

This  is  the  older  and  more  incomplete  process  of  extract- 
ing the  fat.  The  bones  are  placed  in  a  boiler,  covered  with 

(74) 


MANUFACTURE    OF    BONE-GLUE.  75 

water  so  that  it  stands  a  few  inches  deep  over  them,  and  the 
whole  is  boiled  over  an  open  fire.  The  melted  fat  collecting 
on  the  surface  of  the  water  is  skimmed  off.  By  boiling,  a 
portion  of  the  glue-yielding  substance  is,  of  course,  con- 
verted into  glue,  and  passes  into  the  water.  In  order  not 
to  lose  this  glue,  the  same  water  is  repeatedly  used  for  boil- 
ing fresh  quantities  of  bones,  and  is  finally  used  for  feeding 
pigs.  By  this  method  4  to  5  per  cent,  of  fat  is  at  the  utmost 
obtained. 

The  bone  fat  obtained  by  direct  boiling  of  the  bones,  is, 
if  entirely  fresh  material  has  not  been  used,  of  very  inferior 
quality.  It  is  dark  yellow  to  deep  brown  and  of  a  dis- 
agreeable odor.  It  is  only  fit  for  certain  purposes,  and  to 
be  utilized  in  the  manufacture  of  soap  has  to  undergo  a 
special  process  of  purification,  whereby  it  is  rendered  white 
and  odorless. 

2.    STEAMING  BONES. 

In  order  to  obtain  a  larger  quantity  of  fat  than  is  possi- 
ble by  boiling,  the  bones  are  preferably  steamed,  i.  e.,  sub- 
jected to  the  action  of  high-pressure  steam.  This  is  effected 
in  a  closed  cylinder  of  thick  boiler-plate,  into  which  steam 
of  J  to  1  atmosphere  pressure  is  admitted.  The  cylinder  is 
provided  with  a  perforated  false  bottom  upon  which  the 
bones  are  placed.  By  steaming  for  two  or  three  hours,  all 
the  fat  is  extracted  from  the  bones  and  collects,  together 
with  the  condensed  water  formed  by  the  steam  coming  in 
contact  with  the  cold  bones,  underneath  the  false  bottom. 
However,  by  the  continued  action  of  high-pressure  steam 
upon  the  bones,  a  considerable  portion  of  the  glue-yielding 
tissue  is  converted  into  glue,  which  passes  into  the  resulting 
liquor.  This,  however,  is  no  drawback  if  only  fat  and  glue 
are  to  be  obtained  from  the  bones,  since  by  continued 
steaming,  a  liquor  still  richer  in  glue  results,  and  need  only 
be  evaporated.  But,  as  a  rule,  the  greater  portion  of  the 
bones,  especially  the  granulated  parts,  are  to  be  utilized  in 


76  GLUE,    GELATINE,    CEMENTS,    PASTES. 

the  manufacture  of  animal  charcoal,  and,  hence,  great  care 
has  to  be  observed  in  steaming. 

Animal  charcoal  is  produced  by  calcining  bones  in  ves- 
sels from  whicli  the  air  is  excluded,  whereby  the  glue- 
yielding  tissue  is  converted  into  carbon,  which  is  distri- 
buted upon  the  bone-earth.  Since  the  value  of  animal 
charcoal  depends  on  the  quantity  of  carbon  it  contains,  a 
product  prepared  from  bones  highly  steamed,  will  evidently 
be  of  little  value,  as  a  considerable  portion  of  the  glue- 
yielding  substance  has  been  converted  into  glue. 

If  the  bones  are  to  be  used  for  the  production  of  animal 
charcoal  they  should  be  subjected  to  the  action  of  high- 
pressure  steam  only  long  enough  to  extract  the  fat,  but  the 
resulting  glue-liquor  is  very  thin  and  difficult  to  work. 
The  watery  glue-liquor  is  first  drawn  off,  and  the  fat  which 
comes  last  is  caught  by  itself.  The  thin  glue-liquor  is 
evaporated  in  vacuum. 

3.    EXTRACTION  OF  BONES. 

To  avoid  the  loss  of  glue-yielding  substance  which  is  un- 
avoidable in  steaming  bones,  even  if  only  for  a  short  time, 
in  many  plants  the  fat  is  now  extracted  by  treating  the 
bones  with  benzine  or  carbon  disulphide.  No  loss  of  glue- 
yielding  substance  being  involved  by  this  process,  bones 
thus  treated  yield  the  best  quality  of  animal  charcoal. 

The  fat  obtained  by  extraction  with  carbon  disulphide 
has  such  a  disagreeable  odor  as  to  render  it  almost  worth- 
less. In  addition  this  solvent  is  very  volatile,  consequently 
very  inflammable,  and  is  also  very  poisonous.  For  these 
reasons  its  use  for  the  extraction  of  fat  has  been  almost  en- 
tirely abandoned. 

Figs.  31  and  32  show  an  apparatus  for  the  use  of  benzine 
which  is  the  invention  of  Messrs.  Wm.  Adamson  and 
Charles  F.  A.  Simonis,  of  Philadelphia,  Pa.  It  is  for  the 
purpose  of  treating  animal  and  vegetable  substances  with 
hydrocarbons  for  extracting  therefrom  oily,  fatty  and  resin- 


MANUFACTURE    OF    BONE-GLUE. 


77 


ous  matter;  and  the  object  of  this  invention  is  to  cause 
hydrocarbons  to  trickle  through  such  substances  instead  of 
flooding  the  same,  so  that  it  will  take  up  the  oily,  fatty  and 
resinous  matter  without  any  of  the  albuminous  or  gelatin- 
ous ingredients. 

Fig.  31  is  a  vertical  section  of  apparatus  wherewith  this 
invention  may  be  carried  into  effect ;  Fig.  32,  an  inverted 
plan  view  of  part  of  Fig.  31. 

FIG.  31. 


FIG.  32. 


A  is  a  vessel,  preferably  of  cylindrical  form,  and  contain- 
ing an  upper  perforated  diaphragm,  a,  and  lower  perforated 
diaphragm,  6,  the  former  having  a  central  opening,  through 
which  the  material  to  be  treated  may  be  introduced  between 
the  two  diaphragms,  and  this  opening  having  a  detachable 
perforated  cover,  d. 

On  the  top  of  the  vessel  there  is  an  opening,  e,  furnished 
with  a  detachable  cover,  /,  and  at  the  bottom  of  the  vessel 
there  is  an  outlet-pipe,  h,  furnished  with  a  suitable  cock  or 
valve,  i. 


78  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Liquid  hydrocarbon,  preferable  such  as  is  of  a  volatile 
character — benzine,  benzole,  or  gasoline,  for  instance — is 
introduced  into  the  vessel  above  the  diaphragm  a  through 
a  pipe,  H,  and  perforated  ring,  7,  or  otherwise,  the  hydro- 
carbon passing  through  the  diaphragm  and  falls  in  a  shower 
on  the  substance  contained  in  the  vessel. 

The  hydrocarbon  will  trickle  through  the  mass,  taking 
up  whatever  oily,  resinous,  or  fatty  matter  it  comes  in  con- 
tact with  until  it  falls  through  the  lower  diaphragm  inta 
the  space  D,  whence  it  may  be  drawn  off  from  time  to  time 
through  the  outlet-pipe,  h. 

In  extracting  oily,  fatty,  or  resinous  matter  from  vege- 
table or  animal  substances  by  hydrocarbons,  it  has  been 
the  practice  either  to  subject  them  to  hydrocarbon  vapors, 
or  to  immerse  or  steep  the  substances  in  hydrocarbon  until 
the  latter  takes  up  the  oily,  fatty,  or  resinous  matter. 

The  vapor  plan  is  preferable  in  treating  wet  animal  sub- 
stances, such  as  offal ;  but  for  dry  vegetable  or  animal 
matter — seeds,  for  instance,  or  the  residuum  resulting  from 
the  rendering  of  tallow — we  prefer  the  plan  before  described. 

The  flooding  or  steeping  of  animal  or  vegetable  matter  in 
liquid  hydrocarbon  results  in  a  mixture  or  emulsion  of 
gelatinous,  albuminous,  and  fatty  or  oily  matter,  combined 
with  animal  or  vegetable  tissues,  the  whole  forming  an 
amalgamated  mass  ;  hence,  whatever  fatty  or  oily  matter  is- 
extracted  is  accompanied  by  more  or  less  of  the  suspended 
gelatine  or  albumen,  either  of  which  is  more  difficult  to  re- 
move from  the  oil  or  fat,  and  has  a  tendency  to  discolor  the 
same. 

This  difficulty,  it  has  been  found,  can  be  obviated  by  pre- 
venting the  hydrocarbon  from  remaining  in  a  quiescent 
state  in  contact  with  the  material ;  in  other  words,  by 
causing  it  to  trickle  through  the  mass,  which,  by  this  plan, 
retains  its  granular  condition,  and  gives  out  its  oil  or  fat  to 
the  hydrocarbon  without  the  albuminous  or  gelatinous 
matter. 


MANUFACTURE    OF    BONE-GLUE.  79 

In  the  apparatus  before  described,  for  instance,  an  occur- 
rence of  the  objectionable  flooding  of  the  material,  tending 
to  bring  about  the  results  previously  mentioned,  is  obviated 
by  never  permitting  the  extract  in  the  lower  portion  of  the 
vessel  A  to  reach  the  lower  diaphragm  b.  By  drawing  off 
the  extract  from  time  to  time,  any  impediment  to  the  free 
discharge  of  the  hydrocarbon  with  such  oily  and  resinous 
matter  as  it  has  taken  up,  through  the  lower  diaphragm,  is 
prevented,  and  a  continuous  dripping  of  the  hydrocarbon 
through  the  mass  secured. 

The  extract  obtained  by  the  trickling  or  filtering  process 
is  much  more  concentrated  than  that  obtained  by  the  steep- 
ing and  flooding  process. 

Adamson's  Method  for  Treating  Substances  with  Hydrocar- 
bon Vapor  for  the  Purpose  of  Extracting  Oils,  Fats,  etc.  This 
improvement  is  intended  to  prevent  the  fetid  or  other  odors 
imparted  to  the  vapor  from  the  substances  treated  from 
being  recommunicated  to  the  said  substances,  and  to  the 
extracts  obtained  therefrom  through  the  medium  of  the 
vapor  from  the  re-used  hydrocarbon.  The  vapor  is  ob- 
tained from  benzine,  benzole,  etc. 

Fig.  33  represents,  partly  in  section,  the  apparatus 
whereby  the  invention  may  be  carried  into  effect. 

A  is  a  vessel  in  which  the  substances  have  to  be  treated 
by  hydrocarbon  vapor,  the  said  substances  being  intro- 
duced into  the  vessel  through  a  man-hole,  x,  and  deposited 
on  a  perforated  diaphragm,  B,  the  man-hole  being  provided 
with  a  suitable  cover.  A  steam-coil,  D,  is  placed  in  the 
vessel  in  a  space  beneath  the  diaphragm,  and  liquid  hydro- 
carbon is  introduced  into  the  said  space,  and  is  there 
vaporized  by  the  steam-coil.  The  vapor  rising  through  the 
perforated  diaphragm  permeates  the  substance  upon  the 
same,  so  as  to  extract  therefrom  the  oily,  fatty,  or  resinous 
matter,  which  passes  downward  through  the  diaphragm 
into  the  space  below  the  same,  whence  it  may  be  drawn  off 
from  time  to  time  through  the  discharge-pipe  j.  Liquid 


80  GLUE,    GELATINE,    CEMENTS,    PASTES. 

hydrocarbon  may  be  introduced  from  a  tank,  or  from  a 
source  explained  hereafter,  into  the  top  of  the  vessel  A,  so 
that  it  will  pass  through  the  material  and  be  vaporized 
when  it  reaches  the  coil;  the  said  material  being  in  this 
case  subjected  to  a  downward  current  of  liquid  hydrocarbon 
and  an  upward  current  of  vapor. 

Previous  to  this  invention  it  was  Mr.  A  damson's  practice 
to  cause  the  vapor,  after  acting  upon  the  substances  in  the 
vessel,  to  pass  through  a  worm  in  a  condenser,  the  lower 
end  of  the  worm  communicating  with  the  vessel,  A,  be- 
neath the  diaphragm,  as  shown  in  Fig.  35,  p.  85,  so  that 
the  hydrocarbon  was  used  over  and  over  again.  But  in 
practice  this  has  been  found  objectionable  in  many  cases 
for  the  following  reason  : — 

In  treating  animal  offal,  for  instance,  for  the  extraction 
of  fats,  fetid  odors  are  imparted  to  the  hydrocarbon  vapor, 
and  remain,  to  a  considerable  extent,  in  the  condensed 
vapor  when  the  latter  is  restored  to  the  vessel  A',  hence,  the 
fetid  odors  were  recommunicated  both  to  the  fatty  extracts 
and  to  the  material.  The  same  objections  have  been  ex- 
perienced in  treating  meat  for  preservation  and  vegetable 
matter  for  the  extraction  of  oil  by  hydrocarbon  vapor. 

This  difficulty  is  obviated  in  the  following  manner :  The 
vapor-pipe  D'  communicates  with  a  vessel  H  at  the  top  of 
the  same,  and  the  vapor  is  met  by  numerous  small  jets  of 
cold  water — in  the  present  instance,  from  a  perforated 
tubular  ring,  m,  into  which  the  water  is  forced  through  a 
pipe  n. 

Many  different  appliances  may  be  used,  such  as  roses, 
revolving  jets,  etc.,  for  causing  a  spray  through  which  the 
vapor  must  pass,  and  by  which  it  must  be  condensed.  The 
result  of  this  will  be  a  supply,  1,  of  tainted  water  on  the 
bottom  of  the  vessel,  H,  and  a  quantity,  J,  of  washed  and 
purified  hydrocarbon  above  the  water,  the  latter  having 
taken  up  the  fetid  odors. 

The  washed  hydrocarbon  may  be  drawn  off  through  a 


MANUFACTURE    OF    BONE-GLUE. 


81 


pipe,  g,  into  any  suitable  vessel,  and  thence  introduced 
through  the  pipe  h  into  the  vessel  A,  or  may  pass  directly 
into  the  latter  to  be  again  vaporized  therein,  the  vapor  after 
permeating  the  material  and  passing  through  the  pipe  D' 
being  simultaneously  condensed  and  washed  in  the  vessel 
Ht  preparatory  to  being  returned  in  the  condition  of  puri- 
fied liquid  hydrocarbon  to  the  vessel  A. 

By  the  practice  of  this  process,  the  inventor  is  enabled  to 

FIG.  33. 


obtain  a  purer  extract  than  heretofore,  and,  at  the  same 
time,  the  substances  acted  upon  are  more  free  from  noxious 
odors. 

Changes  may  be  made  in  the  apparatus  shown  in  Fig. 
33,  as,  for  instance,  the  vessel  A  may  consist  of  a  horizontal 
6 


82 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


hollow  cylinder,  and  the  vaporizing  of  the  hydrocarbon 
may  be  accomplished  otherwise  than  by  a  steam-coil. 

Adamsoris  Method  for  Treating  Substances  with  Liquid  Hy- 
drocarbon for  the  Purpose  of  Extracting  Oils,  Fats,  etc.  This 
invention  relates  to  a  method  of  treating  animal  and  vege- 
table substances  with  liquid  hydrocarbons,  such  as  benzene, 

FIG.  34. 


benzole,  etc.,  for  the  purpose  of  extracting  from  such  sub- 
stances oils,  fats,  etc. 

The  object  of  this  improvement  is  to  prevent  the  fetid 
and  other  odors  imparted  to  the  liquid  hydrocarbon  by  the 
substances  treated  from  being  recommunicated  to  the  sub- 
stances and  to  the  extracts  therefrom  by  the  liquid  hydro- 
carbon when  re-used. 

In  Fig.  34,  there  is  shown  a  sectional  view  of  apparatus 
whereby  this  invention  may  be  carried  into  effect. 


MANUFACTURE    OF    BONE-GLUE.  83 

A  is  a  vessel  into  which  the  substances  to  be  treated  are 
introduced  through  a  man-hole,  x,  provided  with  a  suitable 
detachable  cover,  and  -through  an  opening  in  the  upper 
perforated  diaphragm,  B,  a  detachable  perforated  plate,  b, 
being  placed  over  the  opening  after  the  substances  have 
been  passed  through  the  same,  the  substances  being  sup- 
ported by  the  lower  perforated  diaphragm,  Bf,  beneath 
which  is  a  space  for  receiving  the  extract  and  liquid  hydro- 
carbon after  the  latter  has  percolated  through  the  mass  in 
the  vessel.  The  extract,  which  occupies  the  lowest  position 
in  the  vessel,  may  be  removed  therefrom  from  time  to  time 
prior  to  being  purified  by  distillation  or  otherwise.  The 
liquid  hydrocarbon  is  permitted  to  pass  from  time  to  time 
through  a  pipe,  d,  into  a  vessel,  D,  where  it  is  met  by  jets 
of  water  from  a  pipe,  /,  the  hydrocarbon  and  water  being 
thoroughly  agitated  in  the  vessel  by  a  revolving  paddle- 
wheel,  E.  This  washing  of  the  liquid  hydrocarbon  may 
be  accomplished  by  different  appliances.  For  instance,  the 
paddle-wheel  may  be  dispensed  with,  and  water  forced  up- 
ward into  the  vessel  from  below  in  the  form  of  numerous 
small  jets.  The  water  and  hydrocarbon  after  this  washing 
operation  are  permitted  to  pass  into  the  subsiding-vessel, 
H,  the  hydrocarbon  being  above  and  the  water  below,  the 
fetid  and  other  odors  divided  by  the  hydrocarbon  from  the 
substances  in  the  vessel,  A,  having,  during  the  washing 
operation,  been  transferred  to  the  water,  which  may  be 
drawn  off  from  time  to  time. 

The  washed  and  purified  hydrocarbon  may  be  pumped 
directly  through  a  pipe,  ra,  into  the  vessel,  A,  to  be  re-used 
for  treating  the  substances  therein  ;  or  it  may  be  pumped, 
first,  into  a  reservoir,  and  permitted  to  flow  from  the  same 
into  the  said  vessel,  A. 

More  or  less  hydrocarbon  is  wasted  by  being  drawn  off 
with  the  extract,  and  to  make  up  for  this  loss  a  supply  may 
be  introduced  at  intervals  from  a  tank  through  the  pipe,  h. 

By  the  practice  of  the  process  described  above,  the  in- 


84  GLUE,    GELATINE,    CEMENTS,    PASTES. 

ventor  is  enabled  to  obtain  a  purer  extract  than  by  the 
ordinary  process  of  treating  substances  with  liquid  hydro- 
carbon.* At  the  same  time  the  substances  treated  will  be 
much  more  free  from  noxious  odors  than  when  the  hydro- 
carbon is  used  over  and  over  again  without  washing. 

It  is  not  essential  strictly  to  adhere  to  the  apparatus 
shown  in  Fig.  34,  as  the  construction  of  the  apparatus  will, 
in  fact,  depend  in  a  great  measure  on  the  locality  in  which 
it  is  to  be  situated. 

Adamson's  Process  for  Removing  Hydrocarbons  from  Sub- 
stances which  have  been  treated  therewith.  This  process  con- 
sists of  washing  from  animal  and  vegetable  substances  the 
hydrocarbon  which  they  retain  after  being  treated  therewith 
for  the  extraction  of  oils,  fats,  etc.,  and  for  other  purposes. 

Different  apparatus  may  be  employed  for  carrying  out 
this  process,  and  it  may  be  conducted  in  the  same  vessel  in 
which  the  material  is  treated  with  hydrocarbon. 

The  vessel,  which  is  shown  in  Fig.  35,  has  been  found  to 
answer  well  for  this  purpose. 

This  vessel  is  furnished  with  a  suitable  detachable  cover, 
«,  and  with  two  perforated  or  wire-gauze  diaphragms,  b  and 
d}  both  extending  across  the  interior  of  the  vessel,  one  near 
the  top  and  the  other  near  the  bottom  of  the  same. 

A  steam-coil,  B,  communicating  with  any  adjacent  steam- 
generator,  is  contained  in  the  vessel  below  the  lower  dia- 
phragm, to  vaporize  the  hydrocarbon,  the  vapor  passing 
through  the  substance  between  the  two  diaphragms  and  out 
through  a  pipe,  Z),  which  passes  through  a  condenser,  E, 
the  latter  restoring  the  hydrocarbon  to  a  liquid  form,  in 
which  it  is  reconveyed  to  the  vessel  through  a  pipe,  D' '. 

In  practicing  the  washing  process  a  pipe,  m,  to  introduce 
water  into  the  vessel,  and  one  or  more  outlet-pipes,  n  n', 
two  in  the  present  instance,  are  necessary.  There  may  also 
be  a  pipe,  p,  through  which  air  can  be  introduced  into  the 
vessel,  under  the  circumstances  explained  hereafter. 

When  the  treatment  of  the  material  in  the  vessel  with 


MANUFACTURE    OF    BONE-GLUE. 


85 


hydrocarbon  vapor  or  liquid  hydrocarbon  has  been  com- 
pleted, steam  is  cut  off  from  the  coil  B,  the  pipes  D  and  Df 
are  closed,  and  the  cover  a  may  be  removed. 

Water  is  now  admitted  through  the  pipe  m  to  the  space 


Fio.  35. 


in  the  vessel  below  the  diaphragm  d,  and  the  cocks  of  the 
outlet-pipes  n  n'  are  opened. 

The  water  permeates  the  material,  passes  upward  through 
the  same,  and  carries  with  it  the  hydrocarbon,  the  latter 
having  a  tendency  to  rise  with  the  water. 

As  the  water,  and  whatever  hydrocarbon  accompanies  it, 


86  GLUE,    GELATINE,    CEMENTS,    PASTES. 

pass  through  the  upper  diaphragm,  b,  the  hydrocarbon  will 
at  once  rise  to  the  surface,  and  will  pass  through  the  upper 
outlet-pipe,  n,  into  any  suitable  receptacle,  the  water  passing 
off  through  the  lower  outlet-pipe. 

If  this  mode  of  separating  the  hydrocarbon  from  the 
water  is  practiced,  the  admission  of  water  to  the  vessel 
should  be  such  in  respect  to  the  outflow  that  the  liquid  will 
remain  at  or  near  a  uniform  level,  that  is,  the  surface  of  the 
liquid  should  bear  the  relation  shown  in  the  drawing  to  the 
upper  outlet. 

The  water  and  hydrocarbon,  however,  may  be  drawn  off 
indiscriminately  into  a  suitable  receptacle,  and  then  separ- 
ated by  decantation ;  but  it  is  advisable  in  all  cases  that  the 
water  should  extend  above  the  mass  of  material  in  the  ves- 
sel, so  that  the  hydrocarbon  can  at  once  rise  to  the  surface 
as  it  escapes  from  the  substance. 

When  the  material  is  of  such  a  character  as  to  be  closely 
packed  and  not  easily  displaced  by  the  upwardly-flowing 
water  (and  this  is  especially  the  case  with  seeds  which  have 
been  treated  with  hydrocarbons),  it  is  necessary  to  agitate 
the  mass,  so  that  the  water  can  gain  access  to  every  part 
thereof.  This  agitation  the  inventor  prefers  to  effect  by  air 
under  pressure  introduced  through  a  pipe,  p,  although 
mechanical  appliances  may  be  used  for  the  purpose. 

It  will  be  understood  that  the  process  may  be  conducted 
in  a  vessel  separate  from  which  the  substances  have  been 
treated  with  hydrocarbon.  A  vessel  similar  to  that  shown, 
for  instance,  but  without  the  coil  and  pipes,  D  Df,  may  be 
used,  and  may  be  furnished  with  trunnions  (shown  by 
dotted  lines)  and  adapted  to  bearings,  so  as  to  be  easily 
tilted  when  its  contents  have  to  be  removed  ;  or  the  vessel 
may  have  an  opening  near  the  lower  diaphragm  for  the 
withdrawal  of  its  contents,  a  suitable  detachable  door  being 
adapted  to  the  opening. 

F.  Seltsam's  apparatus.  In  this  process  the  solvent  is 
boiled  with  the  bones,  previously  coarsely  crushed  and  the 


MANUFACTURE    OF    BONE-GLUE. 


87 


dust  sifted  out,  in  a  strong  closed  vessel,  so  as  to  obtain  a 
higher  temperature,  greater  penetration  and  avoidance  of 
loss.  The  vapor  ascending  condenses  in  the  pores,  extracts 
the  fat  and  collects  under  the  false  bottom  as  a  layer  of 
solution  which  is  subsequently  distilled.  The  apparatus  is 
shown  in  Fig.  36.  The  cylinder,  A,  is  capable  of  with- 
standing a  pressure  of  10  atmospheres,  and  serves  for  the 
generation  of  steam  and  as  an  extracting  vessel.  It  is  filled 
with  bones  and  hermetically  closed.  The  required  quan- 
tity of  solvent  is  then  brought  by  means  of  the  pump,  B, 

FIG.  36. 


from  the  reservoir,  C,  through  the  pipe,  D,  into  the  cylin- 
der, A,  and  the  latter  is  heated.  The  vapors  formed  force 
the  air  through  the  pipe,  E,  into  the  condenser,  F,  where 
any  vapor  which  may  be  carried  along  is  condensed  and 
passes  through  the  pipe,  G,  back  into  the  reservoir,  C. 

When  all  the  air  has  been  expelled  from  the  apparatus 
and  the  pores  of  the  bones,  the  cock  on  the  pipe,  E,  is 
closed.  The  cylinder,  A,  is  then  heated  so  that  a  pressure 
of  a  few  atmospheres  prevails  in  it.  The  vapors  now  act 
energetically  upon  the  bones,  the  dissolved  fat  collecting 
upon  the  cylinder ;  the  cock  on  the  pipe,  H,  is  then  opened, 
and  the  superheated  fluid  discharged  under  high  pressure 


88 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


into  the  distilling  apparatus,  J,  and  the  solvent  is  distilled 
off  from  the  fat  by  means  of  steam.  The  vapors  of  the 
solvent  pass  through  the  pipe,  K,  into  the  condenser,  F, 
and  from  there  back  into  the  reservoir,  (7. 

When  the  manometer  on  A  indicates  no  pressure,  the 
cock  on  the  pipe,  H,  is  closed  and  the  cylinder,  A,  again 
heated,  the  pipe,  E,  being  open,  so  that  any  solvent  still 
adhering  to  the  bones  may  escape  to  the  condenser,  F. 

Figs.  37  and  38  illustrate  Seltsam's  apparatus  as  im- 
proved by  Th.  Richter,  whereby  the  operation  becomes- 

FIG.  37. 


entirely  free  from  danger,  the  vaporization  of  the  solvent 
being  effected  by  steam  only,  and  the  work  is  carried  on 
continuously. 

There  are  two  extracting  vessels,  A  and  B,  of  thick 
boiler-plate,  and  provided  with  false  bottoms,  G,  upon 
which  the  bones  are  placed,  steam  being  admitted  into  the 
space  between  the  true  and  false  bottoms.  The  extracting 
vessels  are  surrounded  by  the  jackets,  C,  and  are  further 
provided  with  the  vacuum  gauges,  E,  and  the  air-cocks,  F~ 


MANUFACTURE    OF    BONE-GLUE.  89 

There  are,  in  addition,  two  other  vessels,  H  and  J,  which 
contain  water,  a  vessel,  K,  for  the  solvent,  and  an  air-pump, 
L.  The  operation  is  carried  on  as  follows : 

The  extracting  vessels,  A  and  B,  are  charged  with  bones, 
all  the  cocks,  with  the  exception  of  M  and  N  closed,  and 


the  air-pump,  L,  is  set  in  motion,  whereby  a  vacuum  is 
formed  in  A.  When  this  is  sufficiently  large,  water  is  ad- 
mitted from  H  through  the  cock  0  into  the  space  P.  The 
water-cock  is  then  closed  and  the  steam-cock,  Q,  opened. 
The  steam  entering  the  space,  R,  brings  the  water  in  P  to 
the  boiling-point,  and  the  air-pump  sucks  off  the  steam 
formed  after  the  cock,  Nt  is  opened.  The  air-pump  is  then 
stopped  and  all  the  cocks  closed,  except  S.  The  solvent 
now  passes  from  the  vessel,  K,  into  the  space  P,  and  after 
closing  the  cock  S,  is  evaporated  by  the  admission  of  steam 
into  R.  The  water-cock  is  then  opened  and  cold  water  ad- 
mitted into  the  jacket  C,  the  solvent  saturated  with  fat 
being  thereby  condensed  in  P.  The  water  is  then  dis- 
charged from  C  and  steam  introduced  into  Rlt  whereby  the 
solvent  is  evaporated  and  forced  into  the  extracting  vessel 
B  by  means  of  the  air-pump,  I/,  after  closing  the  cocks  M 
and  V. 

The  process  is  then  repeated  in  B,  after  a  vacuum  has 
been  created  in  the  same  manner  as  in  A. 

In  the  meanwhile  the  vacuum  in  A  is  interrupted  by 
opening  the  air-cock  F  and  the  fat  drawn  off  through  P  by 
opening  the  cock  U. 


90 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


The  bones  freed  from  fat  are  removed  through  the  man- 
hole D,  and  A  is  charged  with  fresh  material  while  the 
operation  is  carried  on  in  B.  Thus  the  operation  is  contin- 
uous, the  solvent  passing  without  any  loss  whatever  from 
one  extracting  vessel  to  the  other. 

Alfred  Leuner's  apparatus,  Fig.  39,  works  on  the  Soxhlet 

FIG.  39. 


principle,  without  pressure,  using  solvent  and  steam  simul- 
taneously. The  bones  are  placed  in  A  above  the  perforated 
false  bottom  B.  D  is  a  steampipe  by  means  of  which  the 
bones  are  steamed  as  a  preliminary,  the  surplus  stearn  es- 


MANUFACTURE    OF    BONE-GLUE.  91 

caping  through  the  outlet  pipe  E.  After  steaming,  water 
and  benzine  are  run  in  from  the  reservoir  F,  into  the  space 
under  the  false  bottom,  and  heated  by  the  steam  coil  P. 
The  vapors  evolved  are  condensed  in  the  worm  K,  and  at 
first  run  back  over  the  bones  through  the  cock  L,  the  vapor 
passing  upwards  to  the  worm  through  R,  and  the  condensed 
li'quid  being  divided  into  separate  streams  by  the  spreading 
plate  0.  After  some  time  the  cock  G  is  opened  so  that  the 
condensed  liquid  runs  into  the  reservoir  F,  instead  of  flow- 
ing back  into  A.  When  all  the  solvent  has  volatilized 
nothing  but  water  condenses  in  the  worm,  which  is  known 
by  means  of  a  sampling  cock  attached  to  A,  the  draw-off 
cock  E  is  then  opened  and  the  watery  gelatinous  solution 
and  oily  matter  run  off  into  a  suitable  separating  receptacle. 
The  bones  in  A  are  then  discharged  through  a  manhole, 
and  A  being  refilled,  the  whole  operation  is  repeated. 

Extraction  with  hydrochloric  acid.  If  the  bones  are  to  be 
chiefly  worked  for  glue,  extraction  with  hydrochloric  acid, 
which  has  been  referred  to  in  Chapter  III,  under  "  Bones 
and  Cartilages "  may  be  highly  recommended,  the  bones 
being  thereby  freed  from  their  mineral  constituents  and  the 
glue-yielding  substance  remaining  behind  in  a  pure  state. 
The  bones  are  allowed  to  remain  in  contact  with  the  acid 
till  they  are  flexible  and  translucent.  This  may  be  readily 
recognized  by  laying  upon  the  material  in  the  vat  a  bone 
split  in  two.  When  the  latter  by  the  treatment  with  acid 
shows  the  characteristic  appearance  of  swollen  cartilage, 
i.  e.,  has  become  translucent,  extraction  may  be  considered 
complete. 

The  solution  is  then  drawn  off  through  a  tap  imme- 
diately above  the  bottom  of  the  vat  into  stoneware  vessels, 
and  conveyed  to  the  evaporating  pans.  The  tap  is  then 
closed  and  enough  water  to  cover  the  cartilage  is  admitted 
into  the  vat,  and  the  whole  allowed  to  stand  for  a  few 
hours  in  order  to  extract  as  much  as  possible  the  solution 
of  bone-salts  remaining  in  the  cartilage.  The  fluid  is  then 


92  GLUE,    GELATINE,    CEMENTS,    PASTES. 

drawn  off.  It  is  a  quite  concentrated  solution  of  bone-salts 
and,  mixed  with  an  equal  volume  of  hydrochloric  acid, 
may  be  used  for  the  extraction  of  fresh  quantities  of  bones, 
or  be  mixed  with  the  fluid  first  drawn  off  and  evaporated. 

The  further  washing  of  the  cartilage  is  effected  by  re- 
peatedly pouring  water  over  it,  the  operation  being  con- 
tinued until  the  water  running  off  shows  no  acid  reaction. 
Washing  has  to  be  done  very  carefully,  since  glue-solution 
obtained  from  cartilage  containing  but  a  very  small  quan- 
tity of  acid  will  not  congeal.  It  is,  therefore,  advisable  to 
add  to  the  last  wash-water  1  per  cent,  of  soda,  this  quantity 
being  quite  sufficient  for  the  neutralization  of  the  last  traces 
of  acid. 

Sulphurous  acid  process.  In  this  country  sulphurous  acid 
is  largely  employed  in  the  manufacture  of  glue  derived 
from  bones.  When  ordinary  bones  are  treated  with  a  cur- 
rent of  moist  sulphurous  acid  gas,  they  absorb  from  10  to 
12  per  cent,  of  their  weight  of  the  gas  in  the  course  of  12 
hours.  The  amount  may  increase  to  15  or  20  per  cent,  on 
longer  treatment,  but  the  excess  will  then  disappear  on 
exposure  to  air.  Messrs.  Grillo  and  Schroeder  of  Diissel- 
dorf,  who  patented  this  process  in  1894,  believe  that  this  is- 
simply  due  to  the  calcium  phosphate  present  in  the  bones, 
and  remark  that  an  absorption  of  11  to  12  per  cent,  on  the 
gross  weight  amounts  to  16  or  17  per  cent,  of  the  inorganic 
constituents,  and  corresponds  to  the  equation  : 

Ca3(P04)2  +  S02  +  H20  =  2CaHP04  +  CaS03, 

the  sulphurous  acid  simply  acting  in  the  same  way  as  sul- 
phuric acid  does  in  the  manufacture  of  superphosphate,  but 
being  a  milder  acid  than  sulphuric,  the  alteration  of  the 
organic  constituents  which  are  available  for  glue-stock  can 
be  almost  entirely  avoided.  The  acid  phosphate  is  soluble 
in  water,  therefore  the  bones  after  treatment  are  easily  dis- 
integrated by  boiling  water  when  a  large  portion  of  the 
lime  remains  in  the  sediment,  while  the  gelatine  is  dissolved. 


MANUFACTURE    OF    BONE-GLUE.  \)3 

The  process  as  commercially  conducted  is  very  similar  to 
the  well-known  sulphite  method  of  treating  paper  pulp,  and 
is  carried  on  in  iron  cylinders  or  better  in  close  wooden  vats 
lined  with  lead. 

The  gas  is  usually  generated  in  an  impure  form,  with  a 
large  admixture  of  air  and  carbonic  acid,  by  combustion  of 

FIG.  40. 


pyrites  and  coal,  of  crude  sulphur,  or  even  of  only  highly 
pyritous  fuel. 

On  the  other  hand,  since  it  is  well  established  that  the 
absorption  of  a  diluted  gas  is  less  ready,  and  is  more  waste- 
ful than  that  of  a  gas  in  a  pure  state,  the  employment  of  a 
definite  quantity  of  sulphur  dioxide  in  a  concentrated  state, 
either  prepared  by  the  regulated  burning  of  sulphur,  or  the 
decomposition  of  sulphuric  acid,  yields  more  regular  results, 


94  GLUE,    GELATINE,    CEMENTS,    PASTES. 

and  a  product  of  better  quality.  Liquid  sulphur  dioxide,, 
which  is  now  obtainable  at  a  moderate  price  and  in  quan- 
tity, has  the  advantage  that  it  yields  a  continuous  current 
of  pure  gas  of  any  required  rapidity  by  simply  opening  a 
valve,  and  that  the  exact  amount  used  can  be  ascertained 
by  taring  the  containing  vessel  before  and  after  the  opera- 
tion (S.  Rideall). 

The  washed  bones  are  brought  into  the  above-mentioned 
cylinder  or  vat  and  treated  with  a  saturated  solution  of  sul- 
phurous acid.  The  duration  of  the  action  of  the  acid  varies 
according  to  the  condition  of  the  material  and  can  only  be 
determined  by  experience.  The  result  of  the  process  is  a 
liquor  almost  as  clear  as  water,  which,  after  evaporation  in 
the  vacuum  pan,  is  equal  as  regards  clearness  and  lustre,  to 
the  best  quality  of  glue  prepared  from  waste  of  hide  and 
skin.  The  fat  extracted  from  the  bleached  bones  is  lighter 
in  color  and  has  not  the  disagreeable  odor  of  ordinary  bone 
fat,  and  consequently  brings  a  better  price. 

For  the  generation  of  sulphurous  acid  Dr.  Bruno  Terne, 
of  Mass.,  has  constructed  a  very  simple  apparatus  shown  in 
Fig.  40.  The  sulphur  is  burned  in  8;  A  is  the  escape  pipe 
of  stone ;  T,  the  collecting  reservoir ;  P,  the  steam-pump 
for  acid  ;  R,  chimney  for  the  sulphur  burner. 

4.    CONVERSION    OF    CARTILAGE    INTO    GLUE. 

The  conversion  into  glue  of  the  swollen  cartilage  ob- 
tained by  treatment  with  hydrochloric  or  sulphurous  acid 
may  be  effected  by  continued  boiling  in  open  pans  or  in  an 
apparatus  recommended  by  Wm.  Friedberg,  and  shown  in 
Fig.  41. 

The  boiler  K  of  thick  boiler-plate  has  a  diameter  equal  to 
its  height.  Underneath  the  perforated  false  bottom  St  which 
serves  for  the  support  of  the  bones,  lies  a  perforated  steam 
coil  R — D  for  the  introduction  of  steam.  To  this  steam 
coil  is  fitted  a  branch-pipe  d,  which  reaches  into  the  upper 
portion  of  the  boiler  into  which  also  enters  the  water-pipe 


MANUFACTURE    OP    BONE-GLUE. 


95 


W.  The  apparatus  is  further  fitted  with  a  water-gauge,  an 
air  cock,  sampling  cock  and  manhole  for  the  introduction 
of  the  cartilage. 

The  mode  of  operation  with  this  apparatus  is  as  follows : 
The  boiler  is  filled  three-quarters  full  with  cartilage. 
Enough  water  to  fill  the  boiler  one-quarter  full  is  then  ad- 
mitted through  the  pipe  W,  and  the  steam-cock  D  opened. 
The  steam  passing  out  through  the  numerous  perforations 
in  the  coil  E,  is  at  first  condensed  in  the  water,  but  soon 

FIG.  41. 


brings  the  latter  to  the  boiling-point,  and  from  this  stage  on 
begins  the  formation  of  glue.  The  glue  dissolves  in  the 
water,  and  a  sample  of  the  solution  is  from  time  to  time 
drawn  off  through  the  sampling  cock  and  tested  as  to  its 
concentration.  When  the  solution  possesses  the  required 
concentration,  the  admission  of  steam  through  R  is  inter- 
rupted, and  the  cock  d  of  the  branch-pipe  opened,  as  well 
as  the  cock  of  the  discharge  pipe  H,  the  latter  being  opened 
gradually.  The  discharge  pipe  H  is  connected  with  the 
perforated  plate  F,  which  is  covered  with  a  closely-woven 


96  GLUE,    GELATINE,    CEMENTS,    PASTES. 

cloth  and  thus  acts  as  a  filter,  retaining  all  the  solid  par- 
ticles suspended  in  the  glue  solution. 

By  opening  the  cock  d  of  the  branch-pipe,  the  steam- 
pressure  acts  only  upon  the  surface  of  the  fluid,  the  latter 
being  consequently  pressed  with  great  force  through  the 
filter-cloth. 

When  the  hissing  noise  caused  by  escaping  steam  indi- 
cates that  all  the  fluid  has  been  removed  from  the  boiler, 
the  cock  d  of  the  branch-pipe  is  closed,  and  through  a  rose 
fitted  above  the  boiler,  water  is  allowed  to  flow  upon  the 
latter.  By  this  cooling  the  greater  portion  of  the  steam  in 
the  boiler  is  condensed  and  water  may  be  admitted 
through  W. 

The  operation  of  glue-boiling  is  then  commenced  anew 

FIG.  42. 


by  admitting  steam  into  the  steam  coil,  and  continued 
until  the  cartilaginous  mass  has  been  reduced  to  about  one- 
third  of  its  original  bulk,  when  the  apparatus  is  opened, 
fresh  material  introduced,  and  the  whole  operation  repeated. 
In  order  to  be  able  to  replace  the  filter  without  having 
to  empty  the  entire  apparatus,  it  has  been  given  the  shape 
shown  in  Fig.  42.  The  upper  portion  of  the  discharge-pipe 


MANUFACTURE    OF    BONE-GLUE. 


97 


A  is  connected  with  the  lower  portion  by  the  box-screw  H. 
In  the  latter  is  inserted  a  short  cylinder,  C,  with  a  per- 
forated bottom  upon  which  is  placed  the  filter-cloth  ;  the 
latter  is  kept  in  position  by  the  ring  R. 

For  every  apparatus  two  of  the  above-described  filters 
will  be  required.  If,  notwithstanding  a  full  steam  pressure, 
the  glue  solution  runs  off  sluggishly,  it  is  indicative  of  the 
pores  of  the  filter  being  choked  up.  The  screw-box  H  is 

FIG.  43. 


then  removed,  the  filter  taken  out  and  replaced  by  another 
one. 

The  glue  solution  discharged  from  the  apparatus  is  in 
most  cases  sufficiently  clear  to  allow  of  its  being  imme- 
diately evaporated.  However,  for  the  production  of  a  par- 
ticularly fine  quality  of  glue,  it  is  advisable  to  clarify  the 
solution  by  settling.  As  the  liquor  has  to  be  kept  warm  to 
7 


98  GLUE,    GELATINE,    CEMENTS,    PASTES. 

allow  of  the  solid  particles  to  settle,  W.  Friedberg  recom- 
mends the  use  of  the  apparatus  shown  in  Fig.  43.  It  con- 
sists of  an  iron  cylinder  with  a  diameter  equal  to  one-third 
of  its  height.  The  front  of  the  cylinder  is  furnished  with  a 
number  of  cocks  placed  at  equal  distances  from  each  other, 
and  also  with  a  pipe  in  the  slightly  conical  bottom.  It  i& 
surrounded  by  a  wooden  jacket,  the  intermediate  space 
being  filled  with  a  bad  conductor  of  heat.  By  this  arrange- 
ment the  liquor  is  kept  warm  and  in  a  liquid  state  for 
several  hours,  giving  ample  time  for  the  solid  bodies  held 
in  suspension  to  settle  on  the  bottom.  The  condition  of 
the  liquor  is  from  time  to  time  tested  by  allowing  a  small 
quantity  of  it  to  run  into  a  glass  from  the  lowest  cock  in 
front.  If  the  sample  is  perfectly  clear,  the  liquor  may  be 
drawn  off.  If,  however,  after  several  hours'  standing  only 
the  upper  portions  of  the  liquor  are  clear,  while  the  lower 
ones  are  still  turbid,  further  clarification  by  this  means  is 
impossible.  The  upper  portions  of  the  liquor  are  then  used 
for  finer  qualities  of  glue  and  the  lower  ones  for  inferior 
grades. 

By  treating  the  cartilage  with  high-pressure  steam,  a 
liquor  is  obtained  which  on  cooling  congeals  to  quite  a 
solid  jelly,  and  it  might  be  immediately  brought  into  the 
forming-boxes,  cut  into  cakes,  and  dried.  However,  as  the 
drying  of  the  glue  is  one  of  the  most  difficult  operations  for 
the  glue-maker,  it  is  of  great  advantage  to  obtain  the  liquor 
in  as  high  a  state  of  concentration  as  possible  in  order  to 
obtain  a  solid  jelly,  which  causes  the  least  difficulty  in  dry- 
ing. For  this  purpose  the  liquors  leaving  the  clarifying 
vat  with  a  strength  of  about  20  per  cent,  dry  glue  are 
evaporated  down  to  a  strength  of  about  32  per  cent,  in 
winter,  and  35  per  cent,  in  summer.  Evaporation  may  be 
effected  in  open  pans  or  in  vacuum. 

Fig.  44  shows  the  arrangement  of  an  open  evaporating 
pan.  The  copper  pan  P  has  the  form  of  a  shallow  cylinder 
with  a  slightly  conical  bottom,  in  the  lowest  point  of  which 


MANUFACTURE    OF    BONE-GLUE.  99 

is  the  discharge  pipe  for  the  concentrated  liquor.  During 
the  operation  the  discharge  pipe  is  closed  by  the  ball-valve 
Vj  which  can  be  raised  by  the  lever  contrivance  M.  The 
pan  is  surrounded  by  an  iron  steam-jacket ;  the  steam 
passes  in  at  Z>,  and  the  condensed  water  runs  off  at  A.  H 

FIG.  44. 


is  a  sampling  cock  for  taking  samples  to  test  the  concentra- 
tion of  the  liquor. 

To  prevent  the  workroom  from  being  filled  with  steam 
arising  from  the  pan,  the  latter  is  covered  with  a  hood  of 
wood  which  terminates  in  the  pipe  S  projecting  above  the 
roof,  and  a  narrow  pipe  R  branching  off  from  the  steam 
pipe  D  passes  into  8. 

When  vapors  commence  to  arise  from  the  liquor,  the 
cock  on  the  pipe  R  is  slightly  opened  whereby  a  jet  of  steam 
is  blown  into  the  pipe  8,  the  latter  then  acting  as  an  ex- 
hauster, and  the  vapors  in  the  hood  C  are  carried  along  by 
the  jet  of  steam.  By  this  arrangement  no  vapor  passes  into 
the  work-room  and  steam,  is  also  very  rapidly  evolved  from 
the  surface  of  the  liquor. 


100  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Sufficient  steam  should  be  admitted  to  the  pan  for  the 
liquor  to  give  out  an  abundance  of  vapor  without,  however, 
being  brought  to  the  boiling-point,  as  in  that  case  foam 
would  be  formed  and  the  liquor  in  cooling  yield  a  product 
full  of  blisters.  When  the  liquor  has  acquired  the  proper 
degree  of  concentration,  the  admission  of  steam  to  D  and  R 
is  interrupted  and  the  valve  V  having  been  raised  the  liquor 
is  run  into  the  cooling-boxes.  The  latter  are  of  wood  lined 
with  zinc,  or  better  of  stout  zinc  or  heavily  galvanized  iron. 
They  hold  about  J  cwt.  and  are  of  two  shapes :  one  deep 
and  nearly  square,  another  long  and  shallow,  for  quick 
cooling  of  clear  liquors.  Iron  should  not  be  used,  as  it 
readily  rusts  and  causes  discoloration  of  the  glue. 

Cooling  is  effected  by  cold  water  where  it  is  available, 
but  often  merely  by  cold  air,  aided  by  fans  or  blowers,  in  a 
room  protected  from  heat  or  frost.  According  to  S.  Rideal, 
refrigerating  machines  are  now  also  employed,  which,  by 
the  evaporation  of  liquid  gases,  such  as  ammonia,  sulphur- 
ous or  carbonic  acid,  reduce  a  tank  of  brine  to  near  freezing- 
point.  The  temperature  should  not  be  allowed  below  33° 
or  34°  F.,  for  if  frozen  the  jelly  is  hard  and  difficult  to  cut. 
The  brine  circulates  in  iron  pipes  placed  near  the  ceiling  of 
the  room ;  they  must  be  kept  as  clear  as  possible  of  ice  and 
dirt,  and  the  cooling  house  should  be  scrupulously  clean 
and  sweet. 

Spiral  evaporators  are  recommended  by  Thomas  Lam- 
bert as  forming  a  ready  and  economical  means  of  evapora- 
tion. The  evaporator  consists  of  a  spiral  steam  coil,  made 
of  copper,  and  2  inches  in  diameter,  revolving  on  a  centre 
shaft ;  the  lower  half  of  the  coil  is  covered  with  the  glue- 
liquor  in  the  trough.  The  shaft  rests  on  two  plummer- 
blocks,  one  receiving  the  steam,  and  the  other  discharging 
the  spent  steam  and  condensed  water.  The  shaft  is  hollow 
to  the  first  coil,  and  the  steam  is  thus  conveyed  to  the 
spiral.  From  the  last  coil  to  the  end  of  the  plu miner- 
block  the  shaft  is  also  hollow,  and  in  that  portion  resting 


MANUFACTURE    OF    BONE-GLUE.  101 

on  the  block  two  openings  are  made.  In  the  inside  of  the 
plummer-block,  two  openings  are  bored  to  the  outside,  each 
forming  a  covered  channel ;  as  the  shaft  revolves,  all  the 
holes  directly  face  each  other  at  intervals,  and  thus  allow 
any  condensed  water  in  the  coils  to  be  blown  through. 
From  25  to  28  coils  are  generally  used  in  each  spiral.  The 
glue-liquors  are  fed  into  the  trough  at  one  end,  and  have  a 
temperature  of  75°  F. ;  the  temperature  of  the  evaporated 
liquor  is  85°  F.  In  the  rather  slow  passage  through  the 
trough,  the  liquors  receiving  the  heat  of  the  revolving  coils 
are  raised  in  strength  from  20  per  cent,  to  32  per  cent,  dry 
glue,  at  which  point  they  are  ready  for  jellying. 

Vacuum  pans  are  much  used  in  this  country  for  evaporat- 
ing glue-liquors,  though  there  are  some  complaints  made  of 
the  great  waste  owing  to  spray  and  froth  being  carried  off 
in  the  steam.  As  is  well  known  the  boiling-point  is 
lowered  by  increasing  the  pressure  on  the  surface  of  a  fluid. 
By  enclosing  water  in  a  vessel  connected  with  a  constantly 
working  air-pump,  it  is  brought  to  the  boiling-point  by 
heating  to  between  95°  and  104°  F.  The  construction  of 
vacuum  pans  is  based  upon  this  principle,  and  such 
apparatus  is  largely  used  in  many  mauufacturing  processes 
for  evaporating  to  a  certain  degree  fluids,  for  instance,  sugar 
solutions,  which  readily  become  decomposed  at  a  higher 
temperature.  Vacuum  pans  are  also  very  suitable  for  the 
evaporation  of  glue-solution,  especially  in  plants  working 
on  a  large  scale. 

Fig.  45  represents  an  elevation  of  a  vacuum  pan  for  evap- 
orating glue  and  gelatine  liquors  as  described  by  Thomas 
Lambert.  The  pan  is  built  of  steel  plates,  and  lined  out- 
side with  wood  work,  and  rests  on  a  floor  constructed  of 
rolled  steel  plates,  supported  on  four  columns,  with  a  stair- 
way leading  to  the  working  platform.  One  half  of  the 
lower  part  is  shown  in  section,  giving  a  view  of  the  coils  by 
which  the  pan  is  heated.  The  various  parts  are  as  follows  : 
A,  the  body  of  the  pan  ;  B,  the  dome  ;  C,  exhaust  pipe  lead- 


102 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


ing  from  the  dome  to  the  condenser;  D,  condenser;  E,  air 
or  vacuum  pump ;  F,  storage  tank  for  glue  or  gelatine 
liquors,  warmed  with  steam  coil ;  G,  supply  pipe  leading 
from  storage  tank  to  vacuum  pan  ;  H,  discharge  valve ;  J, 
barometer  gauge  for  indicating  vacuum  ;  J,  inlet  steam  pipe 

FIG.  45. 


for  supplying  the  coils ;  K,  exhaust  end  of  vacuum  coils ; 
L,  iron  staircase ;  M,  steel  floor. 

The  accessories  to  the  pan  are  placed  in  a  convenient 
position  above  the  working  floor  and  include  a  steam  gauge 
for  noting  the  pressure  in  the  coils,  a  gauge  for  indicating 
the  height  of  the  liquor  in  the  pan,  vacuum  gauge  1,  as 
shown  in  the  drawing,  air-cocks  and  a  thermometer.  The 
pan  is  also  fitted  with  a  small  apparatus,  by  which  portions 
of  the  boiling  liquor  can  from  time  to  time  be  drawn,  with- 
out disarranging  the  vacuum,  so  that  the  progress  of  evap- 
oration can  be  ascertained. 

In  working  the  pan,  the  storage  tank  F  is  first  filled  with 
the  weak  glue  liquors  to  be  evaporated  ;  the  valve  on  the 
supply  pipe  G  is  then  closed,  and  the  vacuum  pump  set  in 
motion ;  a  few  strokes  are  sufficient  to  reduce  the  internal 
pressure,  and  the  valve  of  the  supply  pipe  is  then  opened, 


MANUFACTURE    OF    BONE-GLUE.  103 

and  the  liquor  allowed  to  fill  up  the  pan  to  the  desired 
mark  on  the  gauge.  The  valve  is  then  closed,  the  steam- 
inlet  valve  J,  supplying  the  coils,  opened.  As  the  heat 
from  the  coils  spreads  through  the  liquor,  the  vacuum  pump 
is  kept  steadily  at  work  reducing  the  inside  pressure  to 
within  2  to  2J  inches  of  a  perfect  Vacuum,  as  seen  on  the 
barometrical  scale.  In  this  vacuum  the  liquor  will  boil  at 
120°  to  130°  F.,  and  the  boiling  is  continued  until  the  with^ 
drawn  samples,  as  tested  by  the  glue-meter,  show  the  desired 
strength.  The  pump  is  then  stopped,  the  vacuum  broken 
by  opening  the  air-cocks,  and  the  concentrated  liquor  is  run 
through  the  valve  H  into  suitably  arranged  receiving  tanks, 
for  supplying  the  trays  or  glasses  for  jellying. 

For  economical  working  with  large  quantities  of  weak 
liquors,  a  combination  of  two,  three  and  even  four  vacuum 
pans,  forming  the  double,  triple  and  quadruple  effect  evap- 
orators, have  been  designed  for  concentration  purposes. 
The  triple  effect  is,  however,  the  system  mostly  in  use,  and 
consists  of  a  grouping  of  three  cylindrical  pans,  each  con- 
nected by  suitably  arranged  piping,  by  which  the  vapors  of 
the  first  pan  are  conveyed  to  and  made  to  heat  the  coils  of 
a  second  pan,  the  resulting  vapors  from  the  second,  passing 
on  to  the  third  pan,  for  a  similar  purpose.  All  the  pans 
are  connected  with  powerful  pumps,  producing  a  nearly 
absolute  vacuum  in  each.  The  liquor  is  evaporated  to  a 
given  density  in  the  first  pan,  and  then  passed  on  to  the 
second,  and  ultimately  to  the  third,  at  which  stage  80  per 
cent,  of  its  water  will  have  been  driven  off. 

To  obtain  in  all  cases  a  product  of  equal  concentration, 
it  is  advisable  to  have  an  instrument  which  will  indicate 
the  amount  of  dry  glue  in  the  solution.  (Fig.  46.) 

By  immersing  a  glass  aerometer  in  the  glue-liquor,  the 
percentage  of  glue  is  indicated  by  a  scale  registering  from 
0  to  70  per  cent,  with  the  jelly  or  glue  solution  at  a  tem- 
perature of  167°  F. 

To  measure  the  temperature  quickly,  a  thermometer  is 


104 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


added,  and  for  the  execution  of  the  entire  test,  a  sheet-iron 
vessel  consisting  of  a  large  and  two  small  tubes,  a,  which 
when  not  in  use,  serve  for  the  reception  of  the  glass  instru- 
ments contained  in  a  special  case.  For  testing,  the  small 
cylinder  is  placed  in  the  large  tube,  a,  and  filled  with  jelly 
by  means  of  the  cap  which  serves  as  a  cover.  The  large 
tube  is  filled  with  hot  water  to  bring  the  jelly  to  the  re- 
quired temperature.  The  two  instruments  are  then 

FIG.  46. 


immersed  in  the  tubes  filled  with  glue-liquors  to  be  tested r 
and  temperature  as  well  as  percentage  can  be  readily 
read  off. 

The  evaporated  and  cooled  glue-liquor  is  cut  into  cakes 
and  dried  in  the  same  manner  as  previously  described. 

5.    PROCESS    FOR    THE    SIMULTANEOUS  UTILIZATION    OF    BONES 
FOR    FAT,  BONE-MEAL    AND    GLUE. 

Manufacturers  frequently  sort  the  bones  in  such  a  way 
that  materials  of  different  quality  are  obtained.  Thickr 
compact  bones  are  utilized  for  the  manufacture  of  animal 


MANUFACTURE    OF    BONE-GLUE.  105 

charcoal,  a  comparatively  small  percentage  of  bone-meal 
resulting  in  crushing  such  bones. 

Incompact,  porous  bones,  on  the  other  hand,  yield  not 
only  crummy  animal  charcoal  of  less  value,  but  in  stamp- 
ing also  a  larger  percentage  of  bone-meal  than  compact 
bones.  Hence  they  are  as  a  rule  directly  worked  for  fat, 
glue  and  steamed  bone-meal,  no  attempt  being  made  to 
convert  them  into  such  granular  pieces  as  are  suitable  for 
the  production  of  charcoal. 

For  this  purpose,  the  bones  are  first  broken  by  a  crusher 
or  mill  into  coarse  pieces,  and  the  fat  extracted  by  a  special 
process  or  together  with  the  glue  in  one  operation.  The 
latter  method  would  seem  to  be  the  most  suitable,  time  and 
labor  being  thereby  saved,  but  it  must  be  borne  in  mind 
that  fat  extracted  by  itself  brings  a  much  better  price  than 
that  obtained  by  steaming,  and  besides  the  yield  of  glue  is 
larger  from  steamed  bones  which  have  been  previously 
degreased. 

The  crushed  bones — whether  degreased  or  not — are  sub- 
jected to  tha  action  of  high-pressure  steam.  The  apparatus, 
Fig.  47,  used  for  this  purpose  consists  of  a  cylinder  of  thick 
boiler-plate,  10  to  13  feet  high  and  3  to  4  feet  in  diameter. 
E  and  A  are  manholes,  which  can  be  closed  steam-tight, 
The  pipe  D  leads  to  the  steam-boiler  and  opposite  to  D  is-  a 
short  pipe,  H.  The  cylinder  is  further  fitted  with  the  per- 
forated false  bottom,  S,  and  the  bent  pipe,  L. 

As  a  rule,  four  to  six,  and  in  larger  plants  even  more,  of 
such  cylinders  are  combined  to  a  battery.  In  this  case  the 
discharge  pipe,  L,  terminates  in  a  common  collecting  ves- 
sel, and  the  steam-pipes,  D,  branch  off  from  a  main  steam- 
pipe.  The  battery  may  be  enclosed  by  brickwork,  but  is 
preferably  placed  upon  a  suitable  foundation  and  sur- 
rounded by  woodwork,  the  intermediate  space  between 
woodwork  and  cylinders  being  filled  with  sawdust.  This 
plan  offers  the  best  means  of  keeping  the  heat  together,  and 
the  further  advantage  that,  in  case  one  of  the  cylinders  be- 


106 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


comes  defective,  it  can  be  readily  taken  out  and  replaced 
by  a  new  one. 

In  order  to  be  able  to  fill  the  cylinders  rapidly  and  with 
the  least  expenditure  of  power,  it  is  advisable  to  place  the 
bone-crusher  at  such  a  height  that  the  crushed  bones  fall 
directly  into  carriages  which  are  run  upon  a  small  railway 

FIG.  47. 


H 


over  the  charging  holes  of  the  cylinders,  and  emptied.  In 
front  of  the  manholes,  A,  for  discharging  the  bones  is  also  a 
railway,  so  that  the  crushed  bones  can  be  directly  emptied 
into  carriages  and  conveyed  to  the  stamping  mill. 

The  cylinder  having  been  filled  with  bones,  is  closed 
steam-tight.  The  cock,  H,  is  then  opened  and  steam  ad- 
mitted by  opening  the  cock  D.  The  steam  passing  in  at 


MANUFACTURE    OF    BONE-GLUE.  107 

first,  is  cooled  off  by  coming  in  contact  with  the  bones  and 
condensed  to  water.  However,  the  temperature  in  the 
cylinder  soon  becomes  so  high  that  the  steam  is  no  longer 
condensed  and,  having  first  expelled  the  air  in  the  cylinder 
through  the  pipe  H,  it  escapes  through  the  latter  in  the  form 
of  a  powerful  jet.  When  this  is  the  case  H  is  closed  and 
high-pressure  steam  allowed  to  act  upon  the  bones. 

The  fat  contained  in  the  bones  melts  and  trickles  down. 
On  the  bottom  of  the  cylinder  collects  a  fluid  which  con- 
tains glue,  is  of  a  milky  turbidity  due  to  admixed  drops  of 
fat,  and  with  a  quite  thick  layer  of  fat  upon  its  surface. 
From  time  to  time — about  every  hour — the  cock  L  is 
slightly  opened.  By  the  pressure  of  the  steam  the  glue- 
liquor  is  expelled  with  great  force  through  the  pipe  L,  the 
latter  being  closed  when  by  the  peculiar  noise  it  is  noticed 
that  only  steam  escapes. 

Steaming  and  the  occasional  discharge  of  melted  fat  are 
continued  until  on  testing  a  sample  of  the  liquor  running 
off,  it  is  noticed  to  be  free  from  fat.  The  liquor  in  the 
cylinder  is  then  expelled  by  the  pressure  of  steam,  the 
steam-cock  D  closed,  the  manhole  A  opened,  and  steam 
again  admitted  through  D.  By  the  steam-pressure  the 
greater  portion  of  the  bones  in  the  cylinder  is  expelled 
through  the  manhole  A.  The  bones  coming  from  the 
cylinder  are  pliable  and  soft,  and,  after  drying,  are  readily 
converted  by  grinding  into  bone-meal. 

For  the  manufacture  of  animal  charcoal  it  is  of  the 
utmost  importance  that  steaming  should  be  interrupted  at 
the  time  when  the  bones  are  completely  degreased.  If, 
however,  only  fat,  glue  and  bone-meal  are  to  be  produced, 
steaming  may  advantageously  be  continued  for  a  longer 
time. 

The  longer  the  bones  are  subjected  to  the  action  of  high- 
pressure  steam,  the  more  complete  the  conversion  of  glue- 
yielding  substance  into  glue  will  be.  To  be  sure,  the  bone- 
meal  obtained  from  such  bones  will  contain  somewhat  less 


108  GLUE,    GELATINE,    CEMENTS,    PASTES. 

nitrogen  than  the  product  from  bones  not  steamed  quite  so 
long.  However,  the  content  of  phosphates  will  in  both 
cases  be  the  same,  and  on  this  depends,  in  the  main,  the 
fertilizing  value  of  bone-meal. 

The  fluid  discharged  from  the  cylinder  consists  of  a  mix- 
ture of  glue-liquor  and  drops  of  fat.  It  is  run  into  a  large 
vat,  in  which  it  is  kept  warm  for  a  few  hours,  when  the  fat 
rises  and  collects  in  a  coherent  mass  on  the  surface.  The 
fat  is  then  drawn  off  through  cocks  in  the  upper  portion  of 
the  vat,  while  the  glue-liquor  is  discharged  from  the  bottom 
of  the  vat,  running  first  upon  a  very  fine  meshed  sieve, 
which  retains  the  coarser  bodies  held  in  suspension,  and 
then  directly  into  the  evaporator.  In  the  latter  the  liquor 
is  evaporated  to  the  desired  strength,  when  it  is  run  into 
the  clarifying  vats,  and  finally  into  the  cooling  vessels. 

With  the  above-described  process,  the  simultaneous 
utilization  of  the  bones  for  animal  charcoal  is  only  possible 
if  the  crushed  steamed  bones  are  passed  through  a  sieve  for 
the  purpose  of  sorting  out  the  granular  pieces  of  suitable 
size.  However,  in  the  process  above  described,  incompact 
bones  are,  as  a  rule,  used  which  give  but  a  small  percentage 
of  granulated  pieces,  and  the  latter  yield  an  inferior  quality 
of  animal  charcoal.  It  is  therefore  best  to  use  the  steamed 
bones  from  which  the  fat  and  glue  have  been  extracted  for 
the  production  of  bone-meal. 

For  the  manufacture  of  animal  charcoal,  the  bones  have 
to  be  carefully  sorted,  fresh  bones  rich  in  organic  substance 
being  best  for  the  purpose,  and  the  hardest  and  thickest 
pieces  should  be  selected.  Previous  to  carbonization,  the 
bones  are  degreased  by  extraction  with  benzine  or  carbon 
disulphide,  and  then  crushed. 

•  Carbonization  was  formerly  effected  in  iron  pots  having 
a  capacity  of  about  25  quarts  each.  However,  by  this 
process  a  uniform  product  of  good  quality  cannot  be  ob- 
tained, and,  besides,  the  total  quantity  of  organic  substance 
of  the  bones  is  lost.  At  present  carbonization  is  effected  in 


MANUFACTURE    OF    BONE-GLUE. 


109 


retorts,  whereby  large  quantities  of  animal  charcoal  are  in 
a  comparatively  short  time  obtained,  and,  besides,  the  pro- 
ducts of  destructive  distillation  can  be  completely  utilized. 
An  essential  product  of  distillation  is  a  large  quantity  of 
inflammable  gases,  which  can  be  used  for  heating  the 
retort-furnace  or  for  illuminating  the  entire  plant,  it  being, 
however,  best  to  arrange  the  conduits  so  that  the  gases  can 
be  used  for  either  purpose. 

A  detailed  discussion  of  the  methods  for  gaining  and 
further  working  of  the  products  of  distillation  is  not  within 
the  scope  of  this  work,  and  only  a  brief  description  of  a 
plant  for  the  manufacture  of  animal  charcoal  will  here  be 
given. 

Figs.  48  and  49  show  the  arrangement  of  a  Belgian 
retort-furnace,  Fig.  48  representing  a  vertical  section 

FIG.  48. 


lengthways,  and  Fig.  49  a  horizontal  section.  The  illustra- 
tions, however,  are  given  at  different  heights  in  order  to 
show  plainly  the  arrangement  of  the  fire-place  and  the 
passage  of  the  fire-gases. 

The  cast-iron  retorts — sixteen  in  the  apparatus  shown — 
are  placed  in  rows  alongside  and  one  after  another,  so  as 
to  be  swept  as  uniformly  as  possible  by  the  fire.  As  will 
be  seen  from  Fig.  49  the  firing  is  so  arronged  that  only  the 
upper  portions  of  the  retorts  are  touched  by  the  flames.  B 
is  the  actual  fire-place,  and  A  the  ash-pit,  both  being  fur- 


110 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


nished  with  closely  fitting  doors  so  that  the  fire  may  be 
properly  regulated,  and  the  retorts  eventually  be  exclu- 
sively heated  with  gas. 

The  retorts  are  cylindrical  in  form,  with  one  end  closed. 
At  the  open  end  is  fixed  the  frame  or  mouth-piece,  which 
carries  the  door  swung  on  a  hinge.  The  door  has  a  slight 

FIG.  49. 


projecting  rim,  some  two  inches  wide,  which,  with  the  sur- 
face of  the  frame,  is  ground  perfectly  true  ;  on  closing,  the 
the  joint  is  made  gas-tight  by  a  lever  arrangement. 

The  fire-gases  escaping  from  B  are  distributed  as  uni- 
formly as  possible  by  the  flues,  a,  carried  underneath  the 
pans,  E,  and  finally  pass  out  in  the  direction  of  the  arrows 
through  a  chimney. 

At  the  time  when  the  extraction  of  fat  was  exclusively 
effected  by  boiling  the  bones,  the  pans  E  served  for  this 
purpose,  and  the  spaces  D,  Dlt  D2,  etc.,  alongside  the  pansr 
which  were  also  heated  by  the  fire-gases,  were  used  for  dry- 
ing the  bones.  However,  at  present,  the  extraction  of  fat 
is,  as  a  rule,  effected  by  means  of  benzine  or  carbon  disul- 
phide,  and  it  is  advisable  to  replace  the  pans,  E,  by  a  bone- 


MANUFACTURE    OF    BONE-GLUE.  Ill 

kiln,  and  eventually  to  utilize  any  waste  heat  for  heating 
the  evaporators  for  glue-liquor. 

Fixed  to  the  upper  portion  of  each  retort  is  a  pipe,  and 
these  pipes  lead  into  a  very  wide  iron-pipe,  T.  The  pro- 
ducts of  destructive  distillation  escaping  from  the  retorts 
combine  in  T,  and  besides  having  a  very  large  diameter, 
this  pipe  must  be  considerably  inclined  to  avoid  the 
accumulation  of  products  of  distillation  in  it.  To  prevent 
the  products  of  distillation  from  depositing  in  a  crystalline 
form  in  T,  the  latter  is  covered  with  a  bad  conductor  of 
heat. 

The  pipe  T  is  connected  with  a  series  of  condensing 
vessels,  D,  another  series  of  vessels  being  placed  alongside 
the  first  one,  so  that  the  vapors  may  be  conducted,  as 
desired,  into  either  one  of  them.  Two  batteries  of  such 
condensing  vessels  are  required,  as  one  of  them  has  from 
time  to  time  to  be  disengaged  in  order  to  be  cleansed. 

If  the  products  of  distillation  would  have  to  overcome 
the  entire  pressure  of  the  column  of  fluid  in  the  condensing 
vessels,  their  escape  from  the  retorts  would  be  very  much 
retarded.  To  avoid  this,  plates  are  arranged  horizontally  a 
few  inches  below  the  level  of  the  fluid,  and  the  pipes  dip 
into  the  condensing  vessels  only  far  enough  to  permit  the 
escaping  vapors  to  pass  under  these  plates.  By  this  ar- 
rangement, the  vapors  sweep  under  the  plates  and.  are 
absorbed  by  the  fluids,  a  strong  pressure  in  the  apparatus 
being  thus  avoided. 

The  condensing  batteries  may  of  course  consist  of  any 
number  of  vessels,  but  as  a  rule  only  a  sufficient  number  to 
retain  all  the  ammonia  is  employed,  five  being  in  most 
cases  sufficient  for  this  purpose.  The  last  condenser  is  con- 
nected with  an  exhaust-pump,  p  p,  which  is  kept  in  motion 
by  a  motor,  P. 

The  pump  removes  all  the  bodies  remaining  in  the  last 
condenser  and  forces  them,  according  to  the  position  of  the 
cock  back  of  the  pump,  either  into  a  glass-bell  or  through 


112  GLUE,    GELATINE,    CEMENTS,    PASTES. 

the  pipe  H  and  the  nozzles  a  into  the  fire-place  where  they 
are  burned. 

To  obtain  the  various  products  of  distillation,  the  con- 
densing vessels  have  to  be  filled  with  acid,  and  should 
therefore  be  constructed  of  lead  or  at  least  of  sheet-iron 
lined  with  lead.  The  products  to  be  obtained  depend  on 
the  fluid  used  for  filling  the  vessels ;  if  filled  with  dilute 
sulphuric  acid,  ammonium  sulphate  is  obtained,  which  may 
be  utilized  in  the  preparation  of  fertilizers.  If  hydrochloric 
acid  is  employed  for  the  absorption  of  ammonia,  solution  of 
ammonium  chloride  is  obtained,  which  may  be  crystallized 
by  evaporation. 

The  products  evolved  in  the  destructive  distillation  of 
bones  consist  of  various  hydrocarbons  and  appear  either  as 
badly-smelling  brown  liquors — bone-tar — or  as  illuminating 
gas.  The  vapors  contain  further  considerable  quantities  of 
ammonium  carbonate  and  cyanide  of  ammonium.  To  ob- 
tain the  latter,  the  last  condensing  vessel  is  filled  with  green 
vitriol  solution,  the  cyanogen  compounds  remaining  behind 
in  the  solution.  If  the  gas  escaping  from  the  last  condenser 
is  to  be  used  for  illuminating  purposes,  it  is  freed  from  the 
greater  portion  of  carbonic  acid  contained  in  it  by  purifica- 
tion with  lime. 

The  mode  of  operation  with  Belgian  retort  furnaces  is  as 
follows :  The  retorts  having  been  filled  with  comminuted 
degreased  bones,  the  doors  are  closed  perfectly  gas-tight  and 
firing  is  commenced.  The  pump  is  set  in  motion  until  a 
jet  of  gas  blows  through  the  nozzles.  When  this  gas-jet 
burns  with  a  luminous  flame,  destructive  distillation  of  the 
bones  is  in  full  blast.  The  pump  is  then  run  with  such 
velocity  that  the  pressure  in  the  interior  of  the  retorts,  as 
indicated  by  the  manometer,  is  slightly  greater  than  the 
external  air-pressure,  and  the  operation  is  thus  continued 
so  long  as  inflammable  gases  escape  from  the  pipe  H.  The 
pump  is  then  stopped,  and  one-half  of  the  charcoal  con- 
tained in  the  retorts  is  withdrawn  to  the  canisters  placed 


MANUFACTURE    OF    BONE-GLUE.  113 

ready  to  receive  it.  The  lids  of  the  canisters  are  then  luted 
down  with  a  paste  of  char-dust  and  water,  making  an  air- 
tight joint,  and  the  charcoal  is  allowed  to  cool. 

The  retorts  having  been  partially  emptied,  are  at  once 
refilled  to  the  brim  with  crushed  bones  and  closed  gas-tight. 
There  is  but  little  or  no  loss  of  heat  between  withdrawing 
and  charging,  and  distillation  of  the  freshly-introduced 
bones  commences  immediately  after  charging,  and  is 
finished  in  a  much  shorter  time  than  in  the  beginning  of 
the  operation. 

In  making  animal  charcoal  on  a  large  scale  there  are 
obtained  from  2000  Ibs.  of  raw  material : 

Animal  charcoal,  1180  to  1220  Ibs. 

Ammoniacal  liquor,  178  to  180  Ibs. 

Gas,  222  to  248  cubic  yards. 

However,  these  figures  refer  only  to  bones  degreased  by 
steaming,  whereby  a  considerable  portion  of  the  cartilagin- 
ous substance  passes  into  solution  in  the  form  of  glue.  In 
working  bones  degreased  with  benzine,  larger  yields  than 
those  indicated  above  are  as  a  rule  obtained.  The  ammo- 
niacal  liquor  contains  on  an  average  10  per  cent,  of  ammo- 
nia. The  gas  freed  from  carbonic  acid  yields  2.7  times  more 
light  than  good  coal-gas. 

6.      PROCESS    FOR    THE    SIMULTANEOUS     UTILIZATION    OF    THE 
BONES    FOR    FAT,    GLUE    AND    CALCIUM    PHOSPHATE. 

This  process  differs  from  the  one  previously  described  in 
that,  in  addition  to  the  total  quantity  of  fat  and  glue- 
yielding  substance  contained  in  the  bones,  the  mineral  salts 
are  also  obtained  in  a  pure  state,  and  can  be  further 
utilized. 

The  bones  are  degreased  either  by  extraction  with  ben- 
zine or  carbon  disulphide  or  steaming,  the  operation  in  the 
latter  case  being  continued  so  long  as  fat  is  yielded  by  the 
bones.  The  resulting  glue-liquor  is  used  in  place  of  water 
for  boiling  the  cartilage. 
8 


114  GLUE,    GELATINE,    CEMENTS,    PASTES. 

The  bones  are  placed  in  large  wooden  vats  furnished 
with  well-fitting  lids,  and  hydrochloric  acid  of  12  per  cent, 
poured  over  them  so  that  they  are  covered  a  few  inches 
deep.  With  the  use  of  acid  of  1.04  specific  gravity  the 
greater  portion  of  the  salts  contained  in  the  bones  will  pass 
into  solution  in  48  to  72  hours,  when  the  solution  is  drawn 
off  as  completely  as  possible  from  the  vats. 

The  residue  in  the  vats  is  treated  with  less  concentrated 
hydrochloric  acid  and  left  in  contact  with  it  until  the  bones 
are  soft  and  flexible  and  the  thinner  pieces  have  become 
translucent,  this  being  a  proof  that  all  the  mineral  salts 
have  been  extracted,  and  nothing  but  pure  cartilaginous 
substance  remains  behind.  The  solution  is  then  drawn  off, 
and  after  pouring  repeatedly  small  quantities  of  pure  water 
over  the  cartilage  to  expel  the  last  remnants  of  acid  liquor, 
it  is  subjected  to  thorough  washing  until  the  last  traces  of 
acid  have  been  removed. 

The  resulting  cartilage  is  white,  translucent,  and  water- 
soaked.  If  left  in  this  state  it  would  of  course  soon  putrefy, 
and  it  is  best  to  work  it  at  once,  or  if  this  cannot  be  done 
it  will  have  to  be  treated  with  carbolic  acid  in  the  manner 
previously  described,  or  dried. 

Drying  the  cartilage  is  time-consuming  work,  and  can 
properly  be  done  only  by  artificial  heat  in  kilns.  If  care- 
fully protected  from  moisture,  thoroughly  dried  cartilage 
may  be  kept  without  injury  for  any  length  of  time.  How- 
ever, before  being  worked  to  glue,  such  material  has  to  be 
again  soaked  in  water  previous  to  the  actual  boiling  opera- 
tion, and  this  process  requires  considerable  time.  It  is 
therefore  best  to  preserve  it  in  carbolic  acid  solution,  which 
only  needs  to  be  drawn  off  when  the  cartilage  is  to  be 
worked,  and  may  be  further  utilized. 

If  boiled  in  open  vessels  with  water,  6  to  8  hours  are 
required  for  the  complete  disintegration  of  the  cartilage. 
In  a  closed  apparatus  under  high  pressure  solution  is 
effected  in  a  much  shorter  time  and  the  operation  pro- 


MANUFACTURE    OF    BONE-GLUE.  115 

gresses  very  smoothly.  With  proper  attention  the  glue 
obtained  from  bones  degreased  with  benzine  and  freed  from 
bone-earth  by  extraction  with  hydrochloric  acid  is,  as  a 
rule,  very  clear,  and  may  be  bleached  with  sulphurous  acid. 

The  extraction  of  the  phosphates  from  bones  may  be 
effected  in  a  very  suitable  manner  as  follows :  A  number  of 
vats  filled  with  bones  are  placed  in  terraces  one  above  the 
other,  and  the  acid  is  allowed  to  run  first  into  the  upper- 
most vat.  After  having  been  for  several  hours  in  contact 
with  the  bones  it  is  discharged  into  the  next  vat,  fresh  acid 
being  run  into  the  first  one,  and  so  on.  By  this  process  a 
highly  concentrated  solution  of  phosphates  is  in  a  few  hours 
obtained  in  the  lowest  vat,  solution  still  adhering  to  the 
bones  in  the  other  vats  being  finally  expelled  by  water. 

However,  the  process  of  extraction  under  decreased  pres- 
sure is  the  most  advantageous,  it  requiring  least  time.  For 
this  purpose  the  bones  are  brought  into  a  vessel  which  can 
be  closed  air-tight  and  the  air  is  expelled.  When  but  a 
slight  air-pressure  prevails  in  the  vessel,  the  cock  of  a  reser- 
voir filled  with  hydrochloric  acid  is  opened,  the  external 
air-pressure  now  forcing  hydrochloric  acid  into  the  extract- 
ing vessel. 

Bones,  as  viewed  under  the  microscope,  consist  of  a  mass 
permeated  with  numerous  minute  tubes  or  pores.  When 
the  air  is  expelled  from  the  vessel  containing  the  bones,  the 
air  in  the  pores  of  the  latter  is  rarefied  and  the  hollow 
spaces  are  filled  with  hydrochloric  acid  whereby  solution  of 
the  phosphates  is  effected. 

The  yield  of  glue  obtained  from  cartilage  after  extraction 
of  the  mineral  constituents  varies  according  to  the  compact- 
ness of  the  bones  used.  Solid  and  compact  bones  yield,  on 
an  average,  15  per  cent,  of  dry  glue,  but  a  comparatively 
large  quantity  of  calcium  phosphate.  On  the  other  hand, 
porous  bones  rich  in  cartilage  yield  from  20  to  25  per  cent, 
of  dry  glue.  The  liquor  obtained  by  treating  the  bones 
contains,  as  previously  mentioned,  calcium  phosphate,  mag- 


116  GLUE,    GELATINE,    CEMENTS,    PASTES. 

nesium  phosphate  and  calcium  chloride  in  solution,  and 
may  be  utilized  in  the  manufacture  of  fertilizers  or  of  phos- 
phorus. 

For  the  first  purpose  which  is  not  very  remunerative,  but 
is  not  very  troublesome,  the  liquor  is  treated  with  milk  of 
lime  until  it  is  slightly  alkaline,  whereby  a  finely  divided 
precipitate  of  basic  calcium  phosphate  is  obtained,  whilst 
calcium  chloride  remains  in  solution.  The  precipitate  is 
allowed  to  settle,  separated  from  the  supernatant  fluid  and 
dried.  The  resulting  product  contains,  on  an  average,  65 
per  cent,  calcium  phosphate,  up  to  20  per  cent,  water  and 
10  to  15  per  cent,  calcium  carbonate,  quick  lime  and  acci- 
dental impurities.  It  forms  an  excellent  fertilizer. 

If  the  liquor  is  to  be  utilized  in  the  manufacture  of  phos- 
phorus, it  is  evaporated  in  shallow  pans  of  glazed  stoneware. 
In  cooling  crystals  of  acid  calcium  phosphate  are  formed, 
which  are  separated  from  the  mother-liquor.  This  subject 
will  be  more  fully  referred  to  in  the  next  chapter. 


CHAPTER  VI. 

MANUFACTURE  OF  PHOSPHOKUS. 

IN  some  instances  the  preparation  of  phosphorus  is  car- 
ried on  in  conjunction  with  other  industries,  for  instance, 
glue-boiling,  the  preparation  of  sal  ammoniac,  yellow  prus- 
siate  of  potash,  etc.  Bone-ash  is  the  chief  material  used  by 
phosphorus  makers.  Many  manufacturers  do  not  burn  the 
bones  to  ashes,  but  purchase  bone-ash,  large  quantities  of 
which  are  brought  from  South  America,  especially  from  the 
Argentine  Republic. 

The  ordinary  method  of  preparing  phosphorus  includes 
the  following  operations : 

1.  Burning   the   bones   and    grinding   the   bone-ash   to 
powder. 

2.  Decomposition  of  the  bone-ash  by  sulphuric  acid,  and 
evaporation  of  the  acid  phosphate  previously  mixed  with 
charcoal. 

3.  The  distillation  of  the  phosphorus. 

4.  The  refining  and  purifying  the  phosphorus. 
Burning  the  bones  to  ash.     The  object  of  the  ignition  of 

the  bones  is  the  complete  destruction  of  the  organic  matter. 
The  operation  is  conducted  in  a  kiln  very  similar  to  those 
in  use  for  burning  lime.  A  layer  of  brush-wood  having 
been  put  on  the  bottom  of  the  kiln,  bones  form  the  next 
stratum,  and  so  on  alternately.  The  wood  having  been 
lighted,  the  combustion  of  the  bones  ensues.  In  order  to 
carry  off  the  fumes,  the  smell  of  which  is  very  offensive,  a 
hood  made  of  boiler-plate  is  placed  on  the  kiln,  and  either 
connected  with  a  tall  chimney,  or  the  smoke  and  gases  are 
conducted  into  the  fire  of  the  kiln  and  burnt.  The  white 
burnt  bones  are  withdrawn  through  an  opening  reserved  in 

(117) 


118 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


the  wall  on  purpose,  the  kiln  being  kept  continuously  in 
operation,  as  in  the  case  with  some  lime  kilns. 

This  kind  of  kiln,  however,  possesses  many  disadvantages, 
and  an  improved  form,  as  proposed  by  Fleck,  is  shown  in 
Fig.  50. 

The  actual  combustion  chamber  consists  of  a  shaft,  A, 
composed  of  two  inverted  cones.  In  the  lowest  portion  of 
the  lower  cone  are  four  or  six  apertures,  b,  which  terminate 
in  inclined  channels  and  serve  as  air-flues,  as  well  as  for 
withdrawing  the  burnt  bones.  Through  the  aperture  a  in 

FIG.  50. 


the  upper  portion  of  the  shaft  additional  bones  may  be  in- 
troduced. This  aperture  is  covered  with  a  heavy  iron  lid. 

As  will  be  seen  from  the  illustration,  the  shaft  contracts 
towards  the  top  in  the  form  of  a  retort  and  passes  into  a 
horizontal  channel  B  which  is  provided,  near  its  beginning, 
with  an  ordinary  fire-place  d.  The  gases  and  fumes  escap- 
ing from  the  burning  bones  must  pass  over  the  flame  of  the 
fire-place  d,  and  are  thereby  so  completely  consumed  to 
water,  carbonic  acid  and  free  nitrogen  that  no  odor  is  per- 
ceptible even  in  the  immediate  neighborhood  of  the  kiln. 

In  order  not  to  lose  the  heat  yielded  by  the  fire-place  d 
and  the  burning  vapors,  the  channel  B  is  covered  with 
shallow  pans  P,  for  the  evaporation  of  such  fluids  as  have 
to  be  subjected  to  this  treatment  in  the  factory. 

The  mode  of  operation  with  a  kiln  of  this  construction  is 


MANUFACTURE    OF    PHOSPHORUS.  119 

as  follows  :  The  shaft  is  filled  two-thirds  full  with  bones  and 
dry  wood  split  in  small  pieces  is  placed  in  the  channels 
b  and  simultaneously  ignited.  Four  or  six  long  hot  flames 
thus  strike  the  bones,  the  latter  becoming  in  a  short  time  so 
highly  heated  that  they  commence  to  burn  briskly  and 
ignite  fresh  portions  of  bones  introduced  through  the  aper- 
ture a. 

The  white  burnt  bones  in  the  lower  portion  of  the  kiln 
are  withdrawn,  while  in  a  glowing  state,  by  means  of  iron 
hooks ;  the  next  layer  of  bones  sinks  down  arid  fresh 
material  is  introduced  through  a,  the  kiln  being  thus  kept 
continuously  in  operation. 

The  quantity  of  substance  which  remains  after  burning 
the  bones  depends  of  course  on  the  quality  of  the  material 
used.  Tubular  bones  of  old  animals  contain  the  largest 
quantity  of  mineral  substance,  and  give  a  much  more 
abundant  yield  of  bone-ash  than  the  spongy  bones  of 
younger  animals.  On  an  average  100  parts  by  weight  of 
fresh  bones  yield  55  parts  by  weight  of  bone-ash.  The 
composition  of  the  latter  is  as  follows : 

Basic  calcium  phosphate,  80  to  84  per  cent. 

Basic  magnesium  phosphate,  2  to  3  per  cent. 

Calcium  carbonate, 


10  to  14  per  cent. 
Calcium  fluoride,     J 

The  bone-ash  thus  obtained  is  converted  into  a  coarse 
powder  by  means  of  machinery,  a  bone-mill  being  best 
suited  for  the  purpose.  Experience  has  shown  that  the 
granules  obtained  by  grinding  should  be  the  size  of  lentils. 
With  the  use  of  larger  pieces  the  acid,  with  which  the  ash 
is  treated  later  on,  does  not  penetrate  the  entire  thickness 
of  the  bone  mass  and  a  portion  of  the  latter  remains  un- 
decomposed.  If  the  granules  are  too  small,  lumps  are 
formed  when  the  ash  is  brought  together  with  the  acid,  and 
the  mass  would  have  to  be  constantly  stirred  in  order  to, 
make  the  action  of  the  acid  effective. 

Decomposition  of  the  bone-ash  by  sulphuric  acid.     When 


120  GLUE,    GELATINE,    CEMENTS,    PASTES. 

the  basic  calcium  phosphate  —  the  constituent  of  the  bone- 
ash  which  conies  here  into  consideration  —  is  brought  in 
contact  with  an  acid  of  sufficient  strength  to  effect  its  de- 
composition, calcium  sulphate  (gypsum)  is  formed,  and  a 
solution  of  acid  calcium  phosphate.  If  the  latter  be  mixed 
with  powdered  charcoal,  evaporated  to  dryness,  and  the 
mixture  exposed,  with  the  exclusion  of  air,  to  a  strong  red 
heat,  the  acid  calcium  phosphate  is  first  converted  into  cal- 
cium metaphosphate,  water  being  yielded.  At  this  high 
temperature  the  calcium  metaphosphate  is  by  the  action  of 
the  carbon  decomposed  to  basic  calcium  phosphate  and 
phosphorus  ;  the  latter  escapes  in  the  form  of  vapor  and 
may  be  caught  in  suitable  condensing  vessels. 

Hence  three  separate  processes  have  to  be  distinguished  : 
1.  The  formation  of  acid  calcium  phosphate  from  the  basic 
calcium  phosphate  contained  in  the  bone-ash.  2.  The  con- 
version of  the  acid  calcium  phosphate  into  calcium  meta- 
phosphate. 3.  Decomposition  of  the  calcium  metaphos- 
phate, phosphorus  being  liberated,  while  basic  calcium 
phosphate  remains  behind. 

Expressed  in  chemical  symbols  these  processes  may  be 
embodied  in  the  following  equations  : 

I.  Ca3(P04)2  +  2H2S04  =  2CaS04  +  CaH4(P04)2 

Basic  calcium        Sulphuric          Calcium  Acid  calcium 

phosphate.  acid.  sulphate  phosphate. 

(gypsum). 


II. 

Acid  calcium  Water.  Calcium 

phosphate.  metaphosphate. 

III.  3Ca(P03)2  +  IOC  -  10CO  f  Ca3(P04)2  =  Pj, 

Calcium         Carbon.     Carbon        Basic  calcium 
metaphosphate.  monoxide.       phosphate. 

If  the  processes  mentioned  under  II.  and  III.  would  pass 
off  in  the  practice  exactly  as  there  stated,  two-thirds,  or  13.3 
per  cent.,  of  the  total  quantity  of  phosphorus  contained  in 


MANUFACTURE    OF    PHOSPHORUS.  121 

the  basic  calcium  phosphate  originally  present  would  be 
obtained.  However,  besides  these  processes,  others  take 
place  which  cause  a  loss  of  phosphorus.  By  the  action  of 
the  red  heat  upon  the  acid  calcium  phosphate,  reciprocal 
action  takes  place  between  the  latter,  the  water  and  carbon, 
so  that  a  portion  of  the  water  is  decomposed,  and  in  addi- 
tion to  carbon  monoxide,  phosphoretted  hydrogen  is  formed  ; 
the  phosphorus  contained  in  the  latter  must  be  considered 
as  lost.  Furthermore,  a  portion  of  the  phosphorus  is  lost 
in  the  form  of  vapor,  even  with  the  use  of  the  best  condens- 
ing contrivances.  In  consequence  of  these  losses  the  actual 
yield  of  phosphorus  is  between  8  and  11  per  cent, 

The  formation  of  acid  calcium  phosphate  may  be  effected 
either  cold  or  with  the  assistance  of  heat,  less  time  being 
required  in  the  latter  case.  The  process  without  the  assist- 
ance of  heat  is  as  follows  : 

The  bone- ash  is  brought  into  a  lead-lined  wooden  tank,  and 
enough  boiling  water  to  cover  it  poured  in.  It  is  then  thor- 
oughly mixed  with  the  water  by  vigorous  stirring  with 
wooden  rakes,  and  the  necessary  quantity  of  sulphuric  acid 
is  then  run  in  with  constant  stirring.  When  an  intimate 
mixture  has  been  effected,  the  tank  is  covered  with  a  well- 
fitting  lid  and  allowed  to  stand  for  a  few  hours.  As  heat 
has  been  liberated  by  the  introduction  of  the  sulphuric  acid 
into  the  mixture  prepared  with  hot  water,  the  entire  mass 
acquires  a  high  temperature. 

Decomposition  is  accelerated  by  stirring  the  contents  of 
the  tank  every  six  hours,  and  the  process  may  be  supposed 
to  be  finished  in  48  hours.  With  the  use  of  fresh  burnt 
ash  no  special  phenomena,  are  observed,  but  if  the  ash  has 
been  prepared  for  some  time  the  caustic  lime  formed  in 
burning  the  bones  has  been  completely  converted  into  car- 
bonate of  lime,  and  the  carbonic  acid  escapes,  causing  a 
slight  foaming  of  the  mass.  In  addition  to  carbonic  acid, 
there  also  escapes  a  certain  quantity  of  hydrogen  fluoride 
gas,  which  is  liberated  by  the  decomposition  of  the  calcium 


122  GLUE,    GELATINE,    CEMENTS,    PASTES. 

fluoride  present  in  the  ash.  This  gas  being,  even  in  very 
small  quantities,  very  injurious  to  health,  the  tanks  should 
be  placed  in  a  thoroughly  ventilated  room. 

When  decomposition  is  complete,  enough  water  is  ad- 
mitted for  the  mass  to  acquire  by  stirring  a  thick  milky 
appearance,  when  it  is  allowed  to  rest  until  it  clarifies  and 
a  perfectly  clear  solution  of  acid  calcium  phosphate  stands 
over  the  precipitate  of  gypsum.  The  clear  solution  is  drawn 
off,  and  the  sediment  washed  with  water  to  obtain  the  solu- 
tion retained  by  it.  For  this  purpose  the  gypsum  is  stirred 
up  with  water,  and  the  thick  fluid  discharged  into  a  filter- 
ing tank.  Upon  the  bottom  of  the  latter  is  a  four-inch-deep 
layer  of  coarse  quartz  sand  ;  upon  this  is  placed  a  false 
bottom,  and  upon  the  latter  is  spread  a  linen  cloth.  The 
liquor  first  running  off  being  milky  is  poured  back  into  the 
tank.  However,  it  runs  off  clear  so  soon  as  the  pores  of  the 
filtering  cloth  have  become  somewhat  contracted  by  the 
gypsum. 

As  a  rule,  the  contents  of  several  filtering  vats  are  run 
into  a  common  filter,  and  the  mass  is  repeatedly  allowed  to 
drain  off.  The  dilute  solutions  thus  obtained  are  evapor- 
ated with  the  first  liquor.  A  third  lixiviation  of  the  sedi- 
ment yields  a  fluid  which  is  used  instead  of  water  in  a  sub- 
sequent operation. 

The  residue  of  gypsum  is  taken  from  the  filtering  tanks, 
and  may  be  used  as  a  fertilizer. 

In  the  warm  way  the  decomposition  of  the  bone-ash  is 
effected  by  providing  the  decomposing  tanks  with  lead 
pipes  through  which  steam  is  introduced,  decomposition 
being  complete  in  24  hours,  ano!  the  first  run  of  solution 
of  acid  calcium  phosphate  reaches  the  evaporating  pan  in  a 
very  hot  state.  The  lixiviation  of  the  gypsum  residue  is 
also  effected  with  water  heated  by  steam,  the  object  of 
separating  the  acid  calcium  phosphate  as  much  as  possible 
from  the  gypsum  being  thus  obtained  more  completely  with 
a  comparatively  small  quantity  of  water  than  is  possible  by 
washing  with  cold  water. 


MANUFACTURE    OF    PHOSPHORUS. 


123 


A  suitable  apparatus  for  hot  lixiviation  is  shown  in  Figs. 
51  and  52  in  cross  section  and  profile.  A  lead-lined  tank, 
13  to  16  feet  in  diameter  and  3J  feet  deep,  is  fitted  with  a 


FIG.  51. 


stirrer  furnished  with  two  or  four  paddles,  and  closed  by  a 
well-fitting  lid.  The  stirrer  is  kept  in  motion  during  the 
entire  operation. 

A  lead  steam  pipe  D  furnished  with  several  narrow  flat 


FIG.  52. 


out-let  pipes  placed  in  the  direction  in  which  the  stirrer 
revolves,  lies  about  4  inches  above  the  bottom  of  the  tank. 
W  is  the  pipe  for  the  admission  of  water,  S  the  lead  pipe 
connected  with  the  sulphuric  acid  reservoir,  and  A  an  out- 
let of  boards  for  carrying  off  the  vapor  evolved  from  the 
mass  in  admitting  the  sulphuric  acid.  R  is  a  wooden 
hopper,  which  serves  for  the  introduction  of  the  bone-ash, 
and  is  removed  when  the  tank  has  been  filled,  the  aperture 


124  GLUE,    GELATINE,    CEMENTS,    PASTES. 

being  closed  with  a  well-fitting  wooden  lid.  The  bottom 
of  the  tank  is  furnished  with  a  lead  discharge-cock. 

Water  is  run  into  the  tank,  the  bone-ash  being  simultan- 
eously introduced  through  the  hopper  R,  and  the  stirrer 
allowed  to  revolve  slowly  to  effect  an  intimate  mixture. 
Sulphuric  acid  and  steam  are  then  at  the  same  time  ad- 
mitted. The  steam  heats  the  fluid  very  quickly  to  the 
boiling-point,  and  assists  the  action  of  the  stirrer,  it  passing 
out  from  the  outlet  pipes  in  the  same  direction  in  which  the 
stirrer  revolves. 

When  the  required  quantity  of  sulphuric  acid  has  been 
introduced,  the  admission  of  steam  is  interrupted,  the 
stirrer,  however,  being  constantly  kept  in  motion.  To  keep 
the  mass  hot,  steam  is  for  a  few  minutes  admitted  every 
hour.  When  the  sulphuric  acid  has  acted  for  24  hours, 
decomposition  is  complete,  and  the  liquor  is  discharged 
through  the  cock  on  the  bottom  of  the  tank. 

For  the  evaporation  of  the  liquor  leaden  pans  are  used, 
and  this  operation  is  continued  until  the  fluid  has  attained 
a  specific  gravity  of  1.45.  The  pans  rest  upon  cast-iron 
plates  covered  with  a  layer  of  clay  or  sand,  to  prevent  them 
from  being  injured  by  the  fire  gases.  For  heating  the 
pans,  the  fire  gases  escaping  from  the  distilling  furnace  or 
the  bone  kiln  are  utilized. 

The  fluid  having  been  evaporated  to  the  above-mentioned 
specific  gravity  is  now  mixed  with  charcoal  powder,  or 
rather  granulated  charcoal  of  the  size  of  small  peas,  in  the 
proportion  of  20  to  25  parts  of  charcoal  to  100  of  liquor. 
The  mixture  is  then  quickly  dried  in  shallow  cast-iron  pans 
heated  by  a  direct  fire.  Much  sulphurous  acid  is  evolved 
during  this  operation,  and  provision  must  be  made  for 
carrying  off  the  vapors  arising  from  the  pans. 

When  the  mass  has  been  dehydrated  so  far  that  it  balls 
together,  it  is  taken  from  the  pan  by  means  of  shovels  and 
brought  into  a  copper  cylinder  which  is  furnished  with  a 
sheet-iron  sieve-like  bottom  through  which  it  is  forced  into 


MANUFACTURE    OF    PHOSPHORUS.  125 

another  pan.  In  this  second  pan  the  mass  is  moderately 
heated  until  a  sample  of  it  still  evolves  slight  vapors  and 
when  pressed  with  the  hand,  after  cooling  somewhat,  ap- 
pears still  moist  without,  however,  being  sticky.  The 
material  is  now  ready  for  distilling  and  100  parts  of  con- 
centrated solution  of  1.45  specific  gravity  and  20  to  25  parts 
of  charcoal  yield  about  77  parts  by  weight  of  so-called  dis- 
tilling mass. 

It  is  best  to  bring  the  hot  mass  as  taken  from  the  pan  at 
once  into  the  retorts,  as  it  is  very  hygroscopic  and,  if  allowed 
to  lie  exposed  to  the  air,  would  absorb  moisture  and  require 
to  be  again  dried.  If  it  cannot  be  immediately  subjected 
to  distillation,  it  is  advisable  to  keep  it  in  sheet-metal  boxes 
tightly  closed. 

The  liquor  obtained  in  treating  bones  for  the  manufacture 
of  glue  with  hydrochloric  acid  may,  as  mentioned  in  Chap- 
ter V,  be  advantageously  utilized  in  the  manufacture  of 
phosphorus.  In  order  to  obtain  in  crystallized  form  the 
acid  calcium  phosphate  contained  in  it,  the  liquor  has  to 
be  concentrated  by  evaporation  and  as  during  this  opera- 
tion hydrochloric  acid  vapors  constantly  escape,  provision 
must  be  made  for  their  removal  from  the  workroom.  The 
operation  is  conducted  as  follows  :  The  flue  of  the  furnace 
for  distilling  the  phosphorus,  through  which  the  fire  gases 
usually  escape  to  the  chimney,  is  made  to  communicate 
with  a  long  low  chamber,  which  can  be  tightly  closed  and 
connects  at  the  other  end  with  a  high  chimney.  The  flue 
is  fitted  with  a  slide  and  by  opening  the  latter,  the  fire 
gases  are  forced  to  pass  through  the  chamber  before  reach- 
ing the  chimney. 

In  the  chamber  are  placed  large,  well-glazed,  earthen- 
ware vessels  which  contain  the  liquor  to  be  evaporated,  the 
vapors  evolved  being  carried  off  by  the  fire-gases  through 
the  chimney.  Evaporation  proceeds  quite  rapidly,  and 
fresh  liquor  is  from  time  to  time  introduced  through  an 
earthenware  pipe,  the  operation  being  repeated  until  a 


126  GLUE,    GELATINE,    CEMENTS,    PASTES. 

sample  taken  from  the  full  vessels  shows  on  cooling  the 
presence  of  an  abundance  of  crystals  of  acid  calcium  phos- 
phate. 

The  admission  of  the  fire-gases  into  the  chamber  is  then 
interrupted,  and  the  contents  of  the  vessels  are  brought  into 
a  wooden  tank  furnished  with  a  stirrer,  which  is  kept  in 
constant  motion  so  that  when  the  liquor  cools,  only  small 
crystals  will  be  formed.  When  crystallization  is  complete, 
the  mother-liquor  is  drawn  off  and  again  evaporated.  By 
this  operation  more  crystals  of  acid  calcium  phosphate  are 
obtained,  which  are,  however,  less  pure  than  those  from  the 
first  liquor.  The  mother-liquor  drawn  off  from  this  second 
yield  of  crystals  might,  on  being  again  evaporated,  give 
more  crystals  which,  however,  would  be  too  impure  to  be 
used  to  advantage. 

To  obtain  the  calcium  phosphate  contained  in  the  last 
mother-liquor,  the  latter  is  exactly  neutralized  with  burnt 
lime,  a  white  precipitate  of  basic  calcium  phosphate  being 
thereby  obtained.  The  precipitate  is  repeatedly  washed  in 
water  and  allowed  to  settle,  and  added  in  small  portions  to 
the  acid  liquors  obtained  by  extracting  the  bones.  As 
these  liquors  always  contain  a  considerable  quantity  of 
hydrochloric  acid  in  excess,  the  basic  calcium  phosphate, 
being  in  a  finely  divided  state,  is  readily  and  completely 
dissolved. 

The  crystals  of  acid  calcium  phosphate  are  removed  from 
the  crystallizing  tanks  by  means  of  wooden  shovels  and 
brought  into  baskets  covered  inside  with  stout  sack-cloth. 
They  are  left  in  the  baskets  until  no  more  mother-liquor 
drains  off,  when  the  cloths  are  folded  together  and  the 
crystals  further  freed  from  liquor  by  pressure.  They  are 
then  heated,  with  constant  stirring,  in  shallow  stoneware 
pans  until  they  are  so  dry  as  to  crumble  of  their  own 
accord.  In  this  manner  small  crystals  of  a  mother-of-pearl 
lustre  are  obtained,  which  feel  like  sharp  quartz  sand  and 
consist  of  pure  acid  calcium  phosphate. 


MANUFACTURE    OF    PHOSPHORUS.  127 

This  mass  is  mixed  with  25  per  cent,  of  its  weight  of 
granulated  charcoal.  The  mixture  is  heated  until  it  is 
pulverulent,  and  then  treated  in  the  same  manner  as  the 
distilling  mass  from  bone-ash. 

In  place  of  stoneware  vessels,  shallow  lead  pans  may  be 
used  for  evaporating  the  liquor  containing  calcium  phos- 
phate. To  prevent  the  melting  of  the  lead  the  pans  are 
bricked  in  under  a  very  flat  arch,  so  that  the  fire  gases  are 
forced  to  pass  close  over  the  liquor,  the  pans  being  kept 
constantly  full.  When  crystallization  is  complete  the  liquor 
is  drawn  off  and  the  pans  are  refilled. 

In  the  manufacture  of  phosphorus  there  is  left  after 
every  distillation  a  residue  of  basic  calcium  phosphate,  and 
it  is  advisable  to  decompose  it  with  hydrochloric  acid,  this 
being  effected  in  a  vat  lined  with  lead  or  coated  with  par- 
affine.  The  mass  is  completely  dissolved,  and  the  black 
sludge  remaining  on  the  bottom  of  the  vat  consists  of  char- 
coal, which  had  been  added  to  the  distilling  mass. 

Distillation  of  the  Phosphorus. — The  distilling  mass  con- 
sists of  acid  calcium  phosphate,  charcoal  and  about  4  to  6 
per  cent,  water.  By  heating  in  the  retorts,  the  acid  calcium 
phosphate  is  first  converted  into  calcium  metaphosphate, 
water  being  eliminated,  according  to  the  following  equation : 

CaH4(P04)2  =  Ca(P03)2  +  2H20. 

By  further  heating  to  a  white  heat  the  calcium  meta- 
phosphate is  so  far  reduced  as  to  yield  two-thirds  of  its  con- 
tent of  phosphorus,  while  one-third  remains  behind  as  cal- 
cium phosphate,  corresponding  to  the  following  equation  : 

3Ca(PO,)3  +  5€foa  =  Ca3(P04)2  +  10CO  +  4P. 
\oC 

The  mixture  of  acid  calcium  phosphate  and  charcoal  is 
distilled  in  glazed  fire-clay  retorts,  12  to  18  of  them  being 
placed  on  each  side  of  a  so-called  galley-furnace.  The 
bodies  of  the  retorts  are  placed  on  the  side  of  the  fire,  while 


128 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


the  necks  pass  through  openings  in  the  walls  of  the  furnace, 
those  portions  of  the  wall  being  only  lightly  bricked  up,  as 
the  retorts,  after  distillation  is  finished  and  the  furnace 
cooled,  have  to  be  removed  in  order  to  clear  out  the  residue 
and  introduce  fresh  mixture.  Between  each  pair  of  retorts 
is  left  a  space  of  5  to  6  inches  for  the  passage  of  the  flames. 
Experience,  however,  has  proved  the  advisability  of  modi- 
fying the  galley-furnace  by  reducing  its  length  and  increas- 
ing its  height,  and  placing  the  retorts  in  two  or  three  rows, 

FIG.  53. 


one  above  the  other.  Two  such  furnaces  are  placed  together 
with  their  narrow  sides,  so  that  the  fire-gases  of  both  meet 
in  a  common  chamber,  and  are  conducted  from  the  latter 
under  the  evaporating  pans.  Four  such  furnaces  may  also 
be  arranged  in  the  form  of  a  cross,  and  their  fire-gases  con- 
ducted into  a  common  chamber.  By  arranging  the  furnace, 
as  is  most  frequently  done,  for  three  double  rows  of  seven 
retorts  each,  it  will  hold  42  retorts,  a  double  furnace  84, 


MANUFACTURE    OF    PHOSPHORUS.  ,129 

and  one  in  the  form  of  a  cross  168.     The  arrangement  of  a 
double  furnace  is  shown  in  Fig.  53. 

The  wall  (7,  which  separates  the  two  fire-places,  serves  for 
supporting  the  lowest  row  of  retorts,  while  the  second  and 
third  rows  rest  upon  intermediate  pieces.  The  fire  gases 
pass  through  flues  into  the  space  over  the  furnace,  the  top 
of  which  may  be  directly  formed  by  the  evaporating  pans. 
It  is,  however,  more  suitable  to  place  the  evaporating  pans 
on  one  side  and  not  run  the  collecting  chamber  for  the  fire 
gases  directly  into  the  chimney.  For  the  introduction  of 
the  retorts  into,  and  their  removal  from,  the  furnace,  a 
narrow  door  is  provided  between  each  two  vertical  rows  of 
retorts.  After  placing  the  retorts  in  the  furnace,  this  door 
is  closed  with  stones  and  the  joints  luted  with  clay. 

Every  three  retorts  lying  one  above  the  other  have  a 
common  receiver,  p,  for  the  collection  of  the  phosphorus 
distilled  off.  The  necks,  r,  of  the  retorts  terminate  in  the 
collecting  pipe,  o. 

The  galley-furnaces,  previously  described,  require  the  use 
of  a  fuel  which  yields  a  very  long  flame,  and  can,  therefore, 
be  heated  only  with  wood  or  very  fat  coal. 

In  order  to  render  possible  the  use  as  fuel  of  coal  yielding 
a  short  flame,  and  especially  of  coke,  furnaces  have  been 
constructed  which  hold  only  a  small  number  of  retorts,  gen- 
erally five,  placed  in  two  rows,  by  twos  and  threes,  one  above 
the  other.  The  retorts  are  cylindrical  in  form,  and  have  a 
capacity  equal  to  that  of  several  smaller  retorts. 

The  receivers  for  collecting  the  phosphorus  distilling  over 
from  the  retorts  are  made  of  clay,  and  should  be  well  glazed 
and  smooth  inside.  Each  receiver  consists  of  two  parts,  one 
of  which  is  a  cylindrical  vessel  open  at  the  top,  into  which 
the  other  part  fits,  and  is  fixed  by  means  of  a  rim,  which  is 
prolonged  so  as  to  form  a  neck,  between  which  and  the  first 
part  is  inserted  a  tube  fitted  on  the  neck  of  the  retort,  while 
the  other  end  of  this  tube  dips  for  about  4  inches  into  the 
receiver,  the  latter  being  filled  with  water. 
9 


130  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Under  certain  conditions  enameled  cast-iron  may  be  used 
as  a  material  for  receivers,  but  the  enamel  must  be  of  such 
a  nature  as  not  to  be  attacked  by  the  phosphorus  vapors, 
otherwise  the  receivers  would  in  a  short  time  be  destroyed. 

The  retorts  having  been  filled  with  the  required  quantity 
of  mixture  are  placed  in  the  furnace  and  the  brick-work  is 
restored.  The  fire  is  then  kindled  and  kept  up  very  gently 
for  some  time  in  order  to  dry  the  fire  clay  used  in  joining 
the  bricks.  The  receivers  are  filled  with  water  and  fitted 
to  the  retorts.  In  each  receiver  a  small  iron  spoon  is  placed 
fastened  to  iron  wire  which  serves  as  a  stem.  After  six  to 
eight  hours  of  firing  the  heat  has  been  so  much  increased 
as  to  cause  the  expulsion  of  any  moisture  left  in  the  mate- 
rial placed  in  the  retorts,  while  quantities  of  hydrocarbon 
gases  and  oxide  of  carbon  are  formed  and  expelled  with  the 
sulphurous  acid.  Subsequently  other  gases  are  given  off, 
and  because  they  contain  some  hydrogen  phosphide  are 
spontaneously  inflammable.  As  soon  as  this  phenomenon 
is  observed  the  joints  of  the  receivers  and  apparatus  con- 
necting it  with  the  retorts  are  luted  with  clay,  care  being 
taken  to  leave,  by  the  insertion  of  an  iron  wire,  a  small 
opening  for  the  escape  of  the  gases,  which  are  as  speedily 
as  possible  removed  by  well  arranged  ventilators  from  the 
building  in  which  the  furnace  is  placed.  The  appearance 
of  amorphous  phosphorus  at  the  small  opening  indicates 
the  commencement  of  the  distillation. 

The  spoon  is  then  placed  in  the  receiver  in  such  a  direc- 
tion that  any  phosphorus  coming  over  may  collect  in  it. 
During  the  progress  of  the  operation,  and  as  long  as  any 
phosphorus  distils  over,  the  evolution  of  combustible  gases 
continues,  and  consequently  a  small  blue-colored  flame  is 
observed  at  the  opening  in  the  lute.  The  water  in  the 
receiver  is  kept  cool  during  the  operation.  After  forty-six 
hours,  with  greatly-increased  firing,  a  full  white  heat  is 
reached,  and  the  quantity  of  phosphorus  coming  over  has 
decreased  so  much  as  to  make  a  continuation  of  the  ignition 


MANUFACTURE    OF    PHOSPHORUS.  131 

process  wasteful.  The  receivers  are  therefore  disconnected 
from  the  retorts. 

The  receivers  are  taken  to  a  special  room  and  entirely 
submerged  in  large  Avooden  troughs  filled  with  water  in 
order  to  drive  off  inflammable  gases  still  contained  in  them 
and  to  cover  the  phosphorus  with  water.  They  should  be 
opened  only  after  this  has  been  done,  and  every  manufac- 
turer should  rigidly  enforce  the  rule  of  carrying  on  the 
operation  in  the  above-described  manner.  Crude  phos- 
phorus is  very  inflammable,  and  when  carelessly  handled 
by  the  workmen  may  inflict  horrible  burns  and,  as  the 
phosphorus  as  a  rule  causes  blood-poisoning,  such  injuries 
generally  cause  death. 

The  phosphorus  is  then  removed  from  the  receivers 
(always  under  water).  The  trough  in  which  this  operation 
is  effected  should  be  provided,  a  few  inches  above  the  actual 
bottom,  with  a  perforated  false  bottom  upon  which  the 
receivers  are  placed.  The  larger  pieces  ^of  phosphorus 
taken  from  the  receivers  are  collected,  under  water,  in 
special  vessels,  while  the  smaller  pieces  fall  through  the 
perforations  of  the  false  bottom  to  the  actual  bottom. 
When  all  the  receivers  have  been  emptied,  the  water  in  the 
trough  is  discharged  into  a  large  barrel  in  which  it  remains 
until  the  particles  of  phosphorus  have  subsided.  The 
water  is  then  drawn  off,  with  the  exception  of  a  sufficient 
quantity  to  cover  the  phosphorus  in  the  barrel. 

The  water  from  the  receivers  as  well  as  from  the  troughs 
shows  a  quite  strong  acid  reaction  due  to  phosphoric  acid, 
which  has  been  formed  by  the  combustion  of  phosphorus 
and  passed  into  solution.  In  order  not  to  lose  this  phos- 
phoric acid,  the  water  is  partly  used  for  filling  the  receivers 
and  partly  for  mixing  the  bone-ash  before  adding  the  sul- 
phuric acid. 

Crude  phosphorus  is  a  mixture  of  crystalline  (ordinary) 
phosphorus  with  amorphous  phosphorus,  the  reddish  color 
of  the  mass  being  due  to  the  latter.  It  further  contains 


132  GLUE,    GELATINE,    CEMENTS,    PASTES. 

phosphorus  irTvarious  stages  of  oxidation,  free  carbon,  and 
if  impure  sulphuric  acid  has  been  used,  arsenic  in  combi- 
nation with  phosphorus. 

Refining  and  purifying  the  phosphorus.  The  crude  phos- 
phorus was  formerly  purified  by  forcing  it  through  the 
pores  of  stout  wash  leather  by  means  of  a  machine.  The 
crude  phosphorus  contained  in  a  tightly  tied  piece  of  wash 
leather  is  placed  on  a  perforated  copper  support  situated  in 
a  vessel  filled  with  water  at  122°  to  140°  F.  As  soon  as 
the  phosphorus  is  molten,  there  is  placed  on  the  wash 
leather  a  wooden  plate  which  by  the  aid  of  a  mechanical 
arrangement  and  a  lever  can  be  forced  downwards  so  as  to 
cause  the  fluid  phosphorus  to  pass  through  the  pores  of  the 
leather,  the  impurities  being  retained.  The  phosphorus  in 
the  form  of  a  slightly  yellowish  fluid  collects  on  the  bottom 
of  the  vessel  and  is  immediately  moulded  into  the  shape  in 
which  it  is  brought  into  commerce.  The  residue  in  the 
wash  leather  consists  chiefly  of  charcoal  dust  and  amor- 
phous phosphorus.  The  wash  leather  can,  as  a  rule,  be 
only  used  once,  and  only  small  quantities  of  phosphorus 
can  be  worked  at  one  time. 

A  more  suitable  process  of  purification  is  as  follows : 
Porous,  unglazed  porcelain  or  earthenware  plates  are  fixed 
in  an  iron  cylinder  connected  with  a  steam  boiler.  The 
cylinder  having  been  hermetically  closed  is  placed  in  a 
vessel  containing  water  at  140°  F.  When  the  phosphorus 
is  molten,  steam  of  a  few  atmospheres'  pressure  is  admitted 
into  the  cylinder,  the  phosphorus  being  thus  forced  through 
the  earthenware  plates. 

The  phosphorus  obtained  by  either  of  these  methods  is 
free  from  mechanically  admixed  particles  of  charcoal  and 
amorphous  phosphorus,  but  it  is  by  no  means  pure,  as  all 
the  substances  dissolved  in  it  (oxides  of  phosphorus)  pass 
through  the  filter.  The  loss  of  phosphorus  amounts  to 
from  5  to  6  per  cent,  of  the  weight  of  the  crude  product. 
The  masses  taken  from  the  filter  plates  are  therefore  col- 


MANUFACTURE    OF    PHOSPHORUS.  133 

lected  and  subjected  by  themselves  to  distillation  in  order 
to  obtain  the  phosphorus  contained  in  them. 

To  obtain  pure  phosphorus,  the  crude  product  has  to  be 
subjected  to  distillation,  this  operation  being  carried  on  in 
iron  retorts  of  a  peculiar  make,  and  shaped  like  the  glass 
retorts  used  in  chemical  laboratories.  The  necks  of  these 
retorts  dip  to  a  depth  of  J  to  j  inch  in  water  contained  in  a 
basin  filled  to  the  rim  so  that  any  phosphorus  which  is  dis- 
charged into  this  water  causes  it  to  overflow.  The  crude 
phosphorus  having  been  fused  under  water  is  next  mixed 
with  12  to  15  per  cent,  of  its  weight  of  moist  sand,  and  this 
mixture  placed  in  the  retorts,  the  object  of  the  mixing  with 
sand  being  to  prevent  the  phosphorus  becoming  ignited 
during  the  filling  of  the  retorts. 

Fig.  54  shows  a  distilling  apparatus.     In  consists  of  a 

FIG.  54. 


cast-iron  retort,  K,  fitted  with  a  cast-iron  dome,  H,  the  joint 
being  made  tight  by  means  of  clay  and  screws.  The  dome, 
A,  tapers  to  a  cone  and  terminates  in  a  wide  glass  tube,  R, 
bent  at  a  right  angle,  and  having  at  the  mouth  a  diameter 
of  about  2  J  inches. 

This  dome,  A,  dips  f  inch  deep  in  water  contained  in  the 
copper  gutter  of  the  receiver  filled  to  the  brim.     The  copper 


134  GLUE,    GELATINE,    CEMENTS,    PASTES. 

receiver,  P,  stands  in  water.  It  contracts  below  in  the 
form  of  a  funnel,  and  terminates  in  a  pipe  closed  by  a  cock, 
Gr,  to  which  is  fitted  a  glass  tube  bent  at  a  right  angle. 

The  retort  having  been  filled  with  the  mixture  of  crude 
phosphorus  and  sand,  the  dome,  H,  is  placed  in  position  and 
the  apparatus  brought  into  the  furnace.  The  dome  is  then 
connected  with  the  condensing  apparatus. 

The  fire  is  so  regulated  that  the  retort  is  uniformly  heated 
from  all  sides  in  order  to  evaporate  as  quickly  as  possible 
the  water  still  adhering  to  the  phosphorus  mixture,  since  at 
a  higher  temperature  the  water  acts  upon  the  phosphorus, 
and  phosphoretted  hydrogen  is  formed.  It  being  scarcely 
possible  to  entirely  avoid  the  formation  of  the  latter,  the 
receiver  has  been  given  the  above-described  form,  so  that 
the  disagreeable  vapors  formed  by  the  ignition  of  the  phos- 
phoretted hydrogen  cannot  escape  into  the  workroom.  The 
gas  escapes  through  the  conical  dome,  A,  and  the  glass  pipe, 
E,  into  the  open  air,  where  it  burns  without  molesting  the 
workmen. 

At  first  steam  only  escapes  from  the  retort,  while  later 
on  phosphoretted  hydrogen  passes  off.  The  evolution  of 
the  latter,  however,  soon  ceases  almost  entirely,  and  the 
phosphorus  distils  uniformly  over.  Heating  is  continued 
until  the  retort  shows  a  slight  red  heat,  all  the  phosphorus 
having  by  that  time  passed  over.  The  residue  in  the 
retort  consists  only  of  sand  and  charcoal. 

The  phosphorus  passing  over  in  the  various  stages  of  dis- 
tillation shows  different  qualities.  The  portion  which 
passes  over  first  is  perfectly  pure,  and  when  cold  presents 
the  appearance  of  bleached  wax  ;  the  portions  passing  over 
later  on  are  of  a  yellowish-red  color,  while  the  last  portions 
are  colored  brick-red  by  amorphous  phosphorus,  and  have 
to  be  collected  by  themselves.  They  are  again  brought 
into  the  retort  in  the  subsequent  operation. 

In  order  to  be  able  to  separate  the  phosphorus  passing 
over  according  to  quality,  the  receiver  for  the  melted  mass 


MANUFACTURE    OF    PHOSPHORUS.  135 

is  fitted  with  a  conical  bottom  furnished  with  a  glass  tube 
which  can  be  closed  by  the  cock  G.  This  glass  pipe  leads 
to  a  tank  filled  with  warm  water,  in  which  the  collecting 
vessel  is  immersed.  The  phosphorus  collecting  in  this 
vessel  is  from  time  to  time  allowed  to  run  into  a  vessel 
filled  with  water,  another  vessel  being  substituted  when  the 
phosphorus  commences  to  show  a  yellowish  color. 

Moulding  the  refined  phosphorus.  It  has  long  been  the 
custom  to  mould  phosphorus  into  the  shape  of  sticks  formed 
by  the  aid  of  a  glass  tube  open  at  both  ends,  one  of  these 
being  placed  in  molten  phosphorus  covered  by  a  stratum  of 
warm  water.  The  liquid  phosphorus  is  sucked  by  the 
operator  into  the  tube  until  it  is  quite  filled.  The  lower 
opening  of  the  tube  being  kept  under  water  is  closed  by  the 
finger  of  the  operator  ;  the  tube  is  instantly  transferred  to  a 
vessel  filled  with  very  cold  water  by  which  the  phosphorus 
is  solidified.  It  is  removed  from  the  glass  tube  by  pushing 
it  out  with  a  glass  rod  or  iron  wire  while  being  held  under 
water. 

Independent  of  its  danger,  the  method  of  moulding  above 
described  is  not  suitable  for  the  manufacture  on  a  large  scale, 
and  various  contrivances  have  been  introduced  for  this  pur- 
pose ;  the  apparatus  constructed  by  Seubert  being  much  used. 
It  consists  of  a  copper  boiler  fitted  on  a  furnace.  To  the  flat 
bottom  of  this  boiler  is  fitted  by  hard  solder  an  open  copper 
trough  communicating  with  a  water-tank.  In  the  boiler  is 
fitted  a  copper  funnel  provided  with  a  horizontal  tube. 
This  portion  of  the  apparatus  is  intended  for  the  reception 
of  the  phosphorus.  At  the  end  of  the  horizontal  tube  is 
placed  a  stop-cock,  while  the  portion  of  the  projecting 
mouth  of  the  tube  beyond  the  cock  is  widened  out  and  fitted 
by  means  of  bolts  and  nuts,  with  a  flange-like  copper  plate, 
into  which  are  inserted  two  glass  tubes.  Into  the  copper 
trough  is  let  a  wooden  partition,  which  serves  the  purpose 
of  supporting  the  glass  tubes  as  well  as  of  preventing  the 
communication  of  the  hot  water  in  the  boiler  and  a  portion 


136  GLUE,    GELATINE,    CEMENTS,    PASTES. 

of  the  trough  with  the  cold  water  of  the  tank  and  the  por- 
tion of  the  trough  nearest  to  it.  The  phosphorus  having 
been  introduced  in  the  boiler,  the  water  is  gently  warmed 
so  as  to  cause  the  fusion  of  the  phosphorus.  As  the  warm 
water  reaches  to  the  wooden  partition,  it  is  evident  that  on 
opening  and  closing  the  cock  at  the  end  of  the  horizontal 
tube,  some  phosphorus  will  pass  through  and  flow  out  of  the 
glass  tubes,  but  that  remaining  in  these  tubes  will  solidify, 
and  on  opening  again  the  cock  at  the  end  of  the  horizontal 
tube,  the  solid  sticks  of  phosphorus  may  be  removed  from 
the  glass  tubes  by  taking  hold  of  the  piece  of  projecting 
phosphorus,  the  phosphorus  being  immediately  immersed 
under  water  in  the  tank,  and  kept  there  protected  from  the 
action  of  the  light. 

Notwithstanding  its  apparently  very  practical  arrange- 
ment, Seubert's  apparatus  possesses  many  disadvantages, 
the  principal  drawback  to  its  use  being  that  the  phosphorus- 
sticks  frequently  stick  so  firmly  in  the  glass  tubes  that  the 
operation  of  moulding  has  to  be  interrupted,  the  tubes 
removed,  and  the  phosphorus  stick  pushed  out  with  a  stout 
wire.  Furthermore,  the  melted  phosphorus  in  flowing  in 
frequently  causes  the  glass  tubes  to  crack. 

Hence  many  factories  have  returned  to  the  old  method 
of  moulding  by  sucking  the  fused  phosphorus  into  glass 
tubes.  To  render  this  operation  perfectly  free  from  danger, 
the  apparatus  shown  in  Fig.  55  has  been  devised,  by  means 
of  which  a  larger  quantity  of  phosphorus  can  in  a  short 
time  be  moulded  into  sticks. 

A  hollow  prism,  P,  of  stout  sheet-iron  is  fitted  at  its  lower 
end  with  8  to  12  short  tubes.  In  the  latter  are  inserted 
air-tight,  by  means  of  rubber,  12  glass  tubes,  G,  each  about 
3J  feet  long  and  somewhat  contracted  at  the  lower  end. 
Two  iron  rods,  E}  are  fitted  to  the  prism  and,  by  means  of 
suitably-shaped  pieces  of  cork,  serve  to  hold  the  glass  tubes 
in  their  proper  position.  To  the  back  of  the  prism  is 
secured  a  rubber  tube,  L,  which  communicates  with  a  small 


MANUFACTURE    OF    PHOSPHORUS. 


137 


air-pump,  and  to  the  upper  surface  of  the  prism  is  fixed  a 
handle. 

The  phosphorus  to  be  moulded  is  fused  in  a  shallow  ves- 
sel of  such  a  shape  that  a  portion  of  it  is  covered  only  about 
2  inches  deep  with  water.  The  glass  tubes  are  placed  in 

FIG.  55. 


the  fused  phosphorus  and  the  air  is  sucked  from  them  by 
means  of  the  air-pump  ;  the  external  air-pressure  forcing  the 
fused  phosphorus  into  the  glass  tube. 

The  tubes  are  now  sufficiently  raised  to  allow  of  a  rubber 
plate  being  pushed  under  their  mouths  in  the  shallower 
portion  of  the  vessel.  The  rubber  plate  is  pressed  against 
the  tubes  and  the  entire  apparatus  placed  in  a  vessel  filled 
with  cold  water.  The  phosphorus  solidifies  very  rapidly  in 
the  lower  narrower  portions  of  the  tubes,  and  the  latter  are 
immediately  detached  from  the  prism  and  replaced  by 
others.  The  phosphorus  when  entirely  cold  is  pushed  from 
the  glass  tubes  by  means  of  a  wire  or  wooden  stick. 

In  some  factories  the  phosphorus  is  moulded  in  wedge- 
shaped  sheet-metal  boxes.  In  packing  two  such  wedges 
are  laid  together  with  their  longitudinal  sides  so  as  to  form 
a  prism. 


138  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Phosphorus  is  stored  either  in  strong  sheet-iron  tanks  or 
in  wooden  boxes  lined  with  tinned  sheet-iron  and  covered 
with  a  stratum  of  water  fully  1 J  inches  deep.  For  shipping 
smaller  quantities  of  phosphorus,  the  sticks  are  packed  in 
tinned  sheet-iron  boxes  and  the  latter  having  been  filled  up 
with  water,  the  lid  is  soldered  on.  To  prevent  the  water 
from  freezing  in  winter,  it  is  advisable  to  mix  it  with  spirits 
of  wine. 

Manufacture  of  phosphorus  with  the  assistance  of  electricity. 
Read  man  and  Parker  have  recently  devised  a  process  for 
the  manufacture  of  phosphorus  on  a  large  scale  in  a  con- 
tinuously working  apparatus  by  means  of  a  powerful  electric 
current,  such  as  is  yielded  by  a  larger  dynamo.  The  mix- 
ture used  for  the  operation  differs  from  the  ordinary  one  of 
calcium  phosphate  and  charcoal,  in  that  it  contains  in  ad- 
dition a  slag-forming  body — a  flux — silicic  acid  (quartz 
sand)  being  at  first  used  for  the  purpose.  Numerous  ex- 
periments, however,  have  shown  kaolin  or  pipe  clay,  i.  e., 
aluminium  silicate,  to  be  more  suitable. 

When  a  mixture  of  calcium  phosphate,  charcoal  and 
aluminium  silicate  is  exposed  to  the  action  of  the  voltaic 
arc  the  following  process  takes  place :  By  the  extraor- 
dinarily high  temperature  prevailing  in  the  proximity  of 
the  arc,  the  reduction  to  phosphorus  of  the  phosphoric  acid 
contained  in  the  calcium  phosphate  is  very  rapidly  effected. 
The  liberated  calcium  combines  immediately  with  the  alu- 
minium silicate  to  a  calcium-aluminium-silicate,  i.  e.,  to  a 
glass  fusible  with  the  greatest  difficulty  which,  however,  at 
the  high  temperature  possessed  by  the  voltaic  arc  becomes 
fluid  like  water. 

The  apparatus  employed  is,  generally  speaking,  similar  to 
the  electric  furnaces  now  in  use.  The  mass  to  be  treated  is 
contained  in  a  carbon  crucible  in  which  the  two  electrodes 
are  placed  opposite  to  one  another,  so  that  the  electric  cur- 
rent must  pass  through  the  mass.  However,  since  the 
phosphorus  at  the  moment  of  liberation  would,  on  coming 


MANUFACTURE    OF    PHOSPHORUS. 


139 


in  contact  with  oxygen,  immediately  burn  again  to  phos- 
phorus pentoxide,  the  apparatus  has  to  be  so  arranged  that 
the  entire  process  passes  off  in  an  entirely  indifferent  gas, 
and  the  condensation  of  the  phosphorus  vapors  takes  place 
under  the  same  conditions. 

Fig.  56  shows  the  apparatus  employed  for  the  electrolytic 
manufacture  of  phosphorus. 

The  carbon  crucible,  a,  is  enclosed   by    a   clay  jacket, 

FIG.  56. 


which  serves  as  an  insulator  of  heat,  and  is  closed  by  a 
graphite  cover,  c.  Through  the  bottom  and  the  cover  of 
the  crucible  pass  the  two  electrodes,  k  k,  which  conduct  the 
current,  and  between  which  the  voltaic  arc  is  formed.  To 
prevent  the  upper  electrode  from  becoming  too  highly 
heated  during  the  operation,  it  is  constantly  cooled  by 
water  admitted  at  g,  and  running  off  at  /.  Through  the 
pipes  h  and  I  an  indifferent  gas — as  a  rule,  illuminating 


140  GLUE,  GF:LATINE,  CEMENTS,  PASTES. 

gas — is  conducted  into  the  apparatus  and  escapes  together 
with  the  phosphorus  vapors  through  the  pipe  d. 

In  operating  with  the  apparatus,  the  reduction  soon  takes 
place,  and  the  phosphorus  vapors  escape  through  <i,  while 
a  thinly-fluid  slag  remains  behind  in  the  crucible.  The 
slag  is  discharged  through  a  pipe  not  shown  in  the  illustra- 
tion, and  a  fresh  charge  of  the  mixture  brought  into  the 
crucible  a,  the  process  of  reduction  being  thus  carried  on 
without  interruption.  The  phosphorus  vapors  escaping 
from  d  are  conducted  through  a  cooled  pipe  and  condense 
to  a  liquid  in  water  heated  to  between  122°  and  140°  F. 
contained  in  a  receiver. 

Although  the  electrolytic  method  of  manufacturing  phos- 
phorus is  of  quite  recent  origin,  a  considerable  portion  of 
the  phosphorus  brought  into  commerce  is  now  prepared  in 
that  manner,  it  being  cheaper  than  the  older  processes 
which  involve  a  very  large  consumption  of  fuel. 


CHAPTER  VII. 

METHODS  OF  BLEACHING  GLUE. 

MANY  experiments  have  been  made  to  bleach  glue,  i.  e.} 
to  obtain  masses  as  colorless  as  possible,  or  at  least  slightly 
colored,  the  resulting  product  being  more  valuable  than  the 
dark-colored  one. 

a.  Bleaching  in  the  Air. 

The  principal  requisite  for  obtaining  a  beautiful  bleached 
glue  is  that  the  unbleached  product  is  clear,  i.  e.}  trans- 
parent, even  if  of  a  dark  color,  this  being  the  best  criterion 
of  well-made  glue. 

Glue  may  be  bleached  whilst  being  prepared,  or  the 
finished  cakes  may  be  subjected  to  the  bleaching  process. 

For  the  purpose  of  obtaining  pale-colored  glue  from  skin 
or  cartilage  it  is  advisable  to  expose  the  materials  in  thin 
layers  to  the  direct  action  of  the  sun.  Moist  oxygen  when 
acted  upon  by  the  sun  is  converted  into  ozone,  which  exerts 
an  extraordinary  bleaching  effect  upon  organic  substances. 

b.  Bleaching  with  Chlorine. 

The  powerful  bleaching  effect  of  a  solution  of  chlorine  in 
water  upon  organic  matter  is  well  known ;  the  water  is 
decomposed,  and  bleaching  is  effected  by  the  oxygen  which 
is  liberated.  Hence  skin  and  cartilage  may  also  be  bleached 
by  placing  them  in  a  vessel  filled  with  weak  solution  of 
chlorine  in  water  and  leaving  them  in  contact  with  it  until 
the  fluid  shows  no  longer  an  odor  of  chlorine.  When 
bleaching  is  finished  the  materials  are  suspended  in  a  cer- 
tain quantity  of  hydrochloric  acid,  which  has  finally  to  be 
removed  by  repeated  treatment  with  water. 

(141) 


142  GLUE,    GELATINE,    CEMENTS,    PASTES. 

c.  Bleaching  with  Animal  Charcoal. 

Animal  charcoal  is  distinguished  by  its  great  power  of 
absorbing  coloring  as  well  as  odoriferous  matter,  and  may 
also  be  used  for  discoloring  glue-liquors.  This  may  be 
done  by  allowing  the  thin  liquor,  as  it  comes  from  the 
glue-boiler,  to  run  through  a  filter  filled  with  animal  char- 
coal, or  with  the  use  of  charcoal  dust. 

In  the  latter  case  the  glue-liquor  is  collected  in  a  clarify- 
ing vessel  and  a  quantity  of  charcoal  dust  amounting  to 
about  3  to  4  per  cent,  of  the  weight  of  the  glue  in  the 
liquor  stirred  in.  The  finely  divided  charcoal  sinks  slowly 
down,  carrying  with  it  the  solid  particles  suspended  in  the 
liquor,  and  collects  on  the  bottom  of  the  clarifying  vessel 
in  the  form  of  a  black  slime. 

In  order  to  discolor  the  glue-liquor  as  much  as  possible, 
when  working  on  a  large  scale,  it  is  recommended  to  use  a 
number  of  cylinders  filled  with  animal  charcoal.  These 
cylinders  are  connected  one  with  the  other  in  such  a  man- 
ner that  the  glue-liquor  runs  into  the  first  cylinder  from 
the  top,  passes  out  from  the  lower  end  of  this  cylinder 
through  a  pipe  into  the  second  cylinder,  traverses  this  from 
bottom  to  top,  passes  into  the  third  cylinder  from  the  top, 
and  so  on.  The  animal  charcoal  in  the  first  cylinder  loses 
its  discoloring  power  first.  The  cylinder  is  then  dis- 
engaged, freshly  charged  and  placed  last  in  the  series  of 
filters,  the  process  being  the  same  with  the  second  cylinder, 
and  so  on,  so  that  after  a  certain  time  all  the  cylinders 
have  alternately  occupied  the  first  and  last  places  in  the 
series  of  filters. 

By  the  use  of  animal  charcoal  it  is  even  possible  to 
render  very  dark  and  badly-smelling  glue,  entirely  colorless 
and  free  from  odor.  The  darker  the  glue  is,  the  longer  it 
must,  of  course,  be  subjected  to  the  action  of  the  animal 
charcoal. 


METHODS    OF    BLEACHING    GLUE. 


143 


d.  Bleaching  with  Sulphurous  Acid. 

Bleaching  of  the  glue-liquor  itself  by  means  of  sulphur- 
ous acid  is  best  effected  in  the  clarifying  vat.  For  this 
purpose,  the  latter  is  fitted  with  a  lead  pipe  reaching  to  the 
bottom  and  terminating  in  a  perforated  coil.  Through 
this  pipe  gaseous  sulphurous  acid,  generated  in  a  suitable 
sulphur-burner  is  forced  through  the  liquor  by  means  of  a 
force-pump. 

The  sulphurous  acid  is  dissolved  in  the  glue-liquor,  the  lat- 
ter being  thereby  bleached.  When  the  liquor  has  acquired 
a  much  paler  color  and  a  strong  odor  of  sulphurous  acid  is 
perceptible  in  the  air  over  the  vat,  the  introduction  of 
gaseous  sulphurous  acid  is  interrupted  and  the  liquor  al- 
lowed quietly  to  clarify,  the  acid  dissolved  in  it  exerting 
during  this  time  a  further  bleaching  effect.  By  this  means 
ordinary  brown  joiners'  glue  of  good  quality  may  be  con- 
verted into  a  pale-yellow  product  similar  to  the  variety 
known  as  gilder's  glue. 

For  bleaching  finished  glue,  solution  of  sulphurous  acid 

FIG.  57. 


in  water  may  be  used,  the  apparatus  shown  in  Figs.  57  and 
58  being  suitable  for  the  purpose. 

The  apparatus  for  the  production  of  the  acid  solution 
consists  of  the  sulphur-burner  0,  the  wash-vessel  for  the 
gas  Wj  and  the  vessel  T  for  dissolving  the  gas  in  water. 

The  sulphur-burner  0  is  a  small  brick  vault  of  sufficient 
size  to  hold  a  vessel  8  having  a  capacity  of  a  few  quarts. 


144  GLUE,    GELATINE,    CEMENTS,    PASTES. 

In  front  the  sulphur-burner  is  provided  with  a  well-fitting 
door  J,  which  is  furnished  with  a  small  aperture  for  the 
introduction  of  an  iron  pipe  into  the  burner.  The  lead- 
pipe  R  leads  from  0  to  the  bottom  of  the  wash-vessel  W, 
and  from  the  lid  of  the  latter  rises  a  pipe  R»  and  runs 

FJG.  58. 


along  the  bottom  of  the  trough  filled  with  water.  This 
trough  is  provided  with  a  wooden  lid  and  the  cock  H,  and 
by  means  of  the  latter  the  fluid  can  be  discharged  into  the 
vessel  G. 

The  trough  T  is  filled  with  water  and  W  is  also  filled 
three-quarters  full.  In  the  burner  0  is  placed  a  dish  S 
filled  with  sulphur,  and  the  latter  ignited.  The  door  is 
then  closed  and  air  blown  in  through  A  by  means  of  a 
bellows,  the  joints  of  the  door  J  being  at  the  same  time 
luted  with  clay. 

In  contact  with  air,  the  sulphur  burns  to  sulphur  dioxide. 
The  latter  is  freed  in  the  wash- vessel  from  sulphur  vapor 
which  has  been  carried  along,  and  passes  from  Rl  through 
the  numerous  perforations  into  the  water  in  T  where  it  is 
dissolved  to  sulphurous  acid. 

Saturation  with  sulphurous  acid  of  the  fluid  in  the  trough 
is  complete  when  the  suffocating  odor  of  the  acid  is  per- 
ceptible in  the  proximity  of  T.  The  fluid  is  then  dis- 
charged, replaced  by  water,  which  is  again  saturated  with 
sulphuric  acid,  and  so  on. 

The  cakes  of  glue  to  be  bleached  are  placed  in  a  trough 
(Fig.  58),  in  which  are  arranged  several  frames,  B,  covered 
with  linen.  The  cakes  of  glue  are  placed  upon  these  frames 
and  the  trough  is  filled  with  sulphurous  acid  so  that  it 


METHODS    OF    BLEACHING   GLUE.  145 

stands  a  few  inches  deep  over  the  uppermost  frame.  The 
cakes  of  glue  swell  up  rapidly  in  the  solution  of  sulphurous 
acid,  and  yielding  up  their  salts  become  bleached.  After 
twelve  hours  the  fluid  is  discharged  through  the  cock,  H, 
and  if  glue  of  a  particularly  fine  appearance  is  to  be  pro- 
duced the  cakes  are  treated  twice  more  with  solution  of 
sulphurous  acid. 

When  bleaching  is  finished  the  trough  is  filled  with 
clean  water,  in  which  the  glue  is  allowed  to  remain  for  a 
few  hours,  when  the  frames  are  lifted  out  and  the  cakes 
dried. 

By  this  method  glue  may  be  bleached  to  such  an  extent 
as  to  render  it  fit  as  a  substitute  for  gelatine  for  many  pur- 
poses, for  instance,  for  the  imitation  of  thin  plates  of  ivory. 

Dr.  Bruno  Terne's  apparatus  (Fig.  40),  previously  de- 
scribed, may  also  be  used  for  the  generation  of  sulphurous 
.acid  for  bleaching  purposes. 
10 


CHAPTER  VIII. 

DIFFERENT  VARIETIES  OF  GLUE  AND  THEIR  PREPARATION. 

BESIDES  the  broadly-distinguished  forms  of  skin-  and 
bone-glue,  the  trade  recognizes  a  large  number  of  varieties, 
distinguished  either  by  their  value  or  their  fitness  for  spe- 
cial purposes. 

•Joiner's  Glue. — This  variety  is  without  doubt  the  oldest 
in  use  and  most  in  demand,  and  its  principal  requisite  is 
its  great  adhesive  power.  It  is  used  for  joining  wood> 
leather,  paper,  etc.,  and  varies  very  much  in  quality  and 
price. 

The  best  variety  is  prepared  from  scraps  of  hide  and 
skin.  A  light  color  not  being  especially  demanded,  there 
existing  rather  a  prejudice  in  favor  of  a  dark-colored  article, 
waste  of  cattle  and  horse  skins  and  tendons  can  be  used  for 
its  manufacture. 

Joiner's  glue,  which  is  generally  preferred  in  thin  cakes, 
is  chiefly  manufactured  in  regular  glue  factories,  though  to 
be  able  to  compete  with  the  bone-glue  turned  out  by  the 
large  establishments,  the  glue-boiler  generally  mixes  skin 
and  bone-glue,  and  is  thus  enabled  to  turn  out  a  tolerably 
good  quality.  The  price  paid  for  the  different  varieties  of 
joiner's  glue  varies  very  much,  being  generally  higher  in 
winter  than  in  summer,  and  is  frequently  more  regulated 
by  the  external  appearance  of  the  article  than  by  its  actual 
value.  Glue  without  gloss,  very  much  warped  and  of  a 
very  dark  color,  may,  notwithstanding  its  faulty  appear- 
ance, possess  excellent  qualities. 

Nothing  need  be  said  about  the  manufacture  of  joiner's 
glue,  since  what  has  been  said  about  the  manufacture  of 
glue  in  general  suffices  for  the  purpose. 

(146) 


DIFFERENT    VARIETIES    OF    GLUE.  147 

How  to  make  and,  use  glue.  Break  the  glue  into  small 
pieces,  put  it  into  an  iron  kettle,  cover  it  with  water,  and 
allow  it  to  soak  twelve  hours  ;  after  soaking  boil  until  done. 
Then  pour  into  a  box  which  can  be  covered  air-tight ;  leave 
the  cover  off  until  cold,  then  cover  up  tight.  As  glue  is 
required,  cut  out  a  portion  and  melt  in  the  usual  way. 
Expose  no  more  of  the  made  glue  to  the  atmosphere  for  any 
length  of  time  than  is  necessary,  as  the  atmosphere  is  very 
destructive  to  made  glue. 

All  glue,  as  received  from  the  factory,  requires  the  addi- 
tion of  water  before  it  will  melt  properly,  and  every  addition 
of  water  (while  the  glue  is  fresh  made)  will,  up  to  a  certain 
point,  increase  its  adhesiveness  and  elasticity.  Some  glues 
will  bear  more  water  than  others,  but  all  will  bear  more 
water  than  usually  falls  to  their  share,  and  that,  too,  with  a 
greater  improvement  in  the  quality  of  the  work.  For  glue 
to  be  properly  effective,  it  requires  to  penetrate  the  pores  of 
the  wood,  and  the  more  a  body  of  glue  penetrates  the  wood 
the  more  substantial  the  joint  will  remain.  Glues  that  take 
the  longest  to  dry  are  to  be  preferred  to  those  that  dry 
quickly,  the  slow-drying  glues  being  always  the  strong- 
est, other  things  being  equal.  Never  heat  made  glue 
in  a  pot  that  is  subjected  to  the  direct  heat  of  the  fire 
or  a  lamp.  All  such  methods  of  heating  glue  cannot 
be  condemned  in  terms  too  strong.  Do  not  use  thick  glue 
for  joints  or  veneering.  In  all  cases  work  it  well  into  the 
wood  in  a  manner  similar  to  what  painters  do  with  paint. 
Glue  both  surfaces  of  your  work  excepting  in  the  case  of 
veneering.  Never  glue  upon  hot  wood,  as  it  will  absorb  all 
the  water  in  the  glue  too  suddenly,  and  leave  only  a  very 
little  residue,  with  no  adhesiveness  in  it  whatever. 

Holding  power  of  glue.  1.  Glue  exerts  a  far  greater  hold 
on  surfaces  of  wood  cut  across  the  grain  than  on  those  that 
have  been  split,  or  cut  with  the  grain. 

2.  When  two  surfaces  of  split  wood  are  laid  together,  the 
hold  of  the  glue  is  the  same  whether  the  fibres  are  laid  par- 
allel or  crosswise  to  each  other. 


148  GLUE,    GELATINE,    CEMENTS,    PASTES. 

3.  The  holding  power  of  glue  on  different  woods  esti- 
mated in  kilogrammes  per  square  centimeter  (0.155  square 
inch)  is  as  follows : 

Cut  across  the  grain.  Split. 

Beech,  155.55  (342.21  Ibs.)  78.83  (173.42  Ibs.) 

Hornbeam,         126.50  (278.30  Ibs.)  79.16  (174.15  Ibs.) 

Maple,  87.66  (192.85  Ibs.)  63.00(138.6    Ibs.) 

Oak,  128.34  (282.34  Ibs.)  55.16  (121.35  Ibs.) 

Fir,  110.50  (243.10  Ibs.)  24.16  (  53.15  Ibs.) 

Cologne  glue.  The  variety  of  glue  known  under  this 
name  is  prepared  from  selected  scraps  of  hide  and  skin,  and 
is  consequently  very  pure,  and  possesses  great  adhesive 
power.  It  is  of  a  light-brown  color,  and  comes  into  com- 
merce in  short  thick  cakes  of  great  hardness.  It  is  an 
excellent  quality  of  glue,  and  is  preferred  to  all  others  by 
bookbinders,  workers  in  leather,  etc.  There  are  many 
imitations  of  this  variety,  bone-glue,  being  frequently  sold 
as  Cologne  glue. 

The  genuine  article  is  manufactured  from  refuse  of  hide, 
which,  after  liming,  is  carefully  bleached  in  a  bath  of 
chloride  of  lime,  the  concentration  of  which  depends  on  the 
darker  or  lighter  color  of  the  glue-stock.  For  220  Ibs.  of 
glue-stock,  it  is  generally  customary  to  use  1  Ib.  of  chloride 
of  lime  mixed  with  sufficient  water  to  cover  the  stock. 

After  thorough  impregnation  of  the  glue-stock,  which 
generally  requires  about  half  an  hour,  add  sufficient  hydro- 
chloric acid  to  impart  an  acid  taste  to  the  bath  of  chloride 
of  lime.  To  be  able  to  mix  the  mass  thoroughly,  it  is  best 
to  use  a  vat  provided  with  a  stirring  apparatus.  After 
allowing  the  acid  to  act  for  a  quarter  of  an  hour,  remove 
every  trace  of  it  by  careful  washing. 

To  obtain  a  jelly  as  clear  as  possible,  the  gelatinous  liquor 
is  drawn  off  as  soon  as  the  thin  portions  of  the  glue-stock 
and  the  outside  of  the  thicker  ones  are  dissolved,  they  being 
more  thoroughly  bleached  than  the  rest.  The  residue  is 
worked  into  darker  glue. 


DIFFERENT    VARIETIES    OF    GLUE.  149 

Russian  glue.  This  variety  is  of  a  dirty  white  color,  and, 
like  Cologne  glue,  is  brought  into  commerce  in  short,  thick 
cakes.  Its  color  and  opaqueness  are  imparted  to  it  by  an 
addition  of  4  to  8  per  cent,  of  white  lead,  chalk,  zinc  white, 
or  permanent  white  (sulphate  of  baryta).  It  has  been 
claimed  that  the  superior  adhesive  power  of  Russian  glue 
is  due  to  this  addition  of  mineral  substances,  but  the  results 
of  many  experiments  fail  to  substantiate  this  claim.  In 
case  the  glue  turns  out  turbid,  it  may  be  of  advantage  to 
make  it  opaque  by  an  addition  of  coloring  matter,  but  the 
quality  of  the  glue  remains  unchanged.  The  best  time  to 
add  the  coloring  matter  is  shortly  before  drawing  the  glue- 
liquor  from  the  clarifying  vats  into  the  cooling  boxes,  as 
the  jelly  is  then  of  sufficient  consistency  to  prevent  the 
substances  from  settling  on  the  bottom.  Skin-glue,  as  well 
as  bone-glue,  is  sold  under  the  name  of  Russian  glue. 

Quite  a  considerable  quantity  of  Russian  glue  brought 
into  commerce  in  the  form  of  brownish-white  sheets  is  pre- 
pared from  bones,  the  latter  being  degreased  by  boiling, 
steaming  or  extraction,  and  the  solution  of  the  mineral  con- 
stituents effected  by  means  of  hydrochloric  acid.  The  treat- 
ment with  acid  is,  however,  continued  only  till  the  bones 
commence  to  become  soft  and  flexible.  The  solution  of 
phosphates  is  then  drawn  off,  and  the  softened  bones  are 
washed  and  in  the  usual  manner  worked  to  glue. 

By  this  incomplete  treatment  with  hydrochloric  acid,  a 
certain  quantity  of  the  phosphates  remains  in  the  cartilage 
and  is  inclosed  in  the  glue  prepared  from  it,  the  finished 
product  acquiring  thereby  a  dirty  whitish  color,  which  is 
by  many  considered  an  evidence  of  its  quality.  This 
mechanical  admixture  of  phosphates,  however,  does  not 
affect  the  adhesive  power  of  the  glue,  neither  increasing  or 
decreasing  it.  Such  white  and  opaque  glue  is  manufactured 
to  answer  the  demand  in  certain  quarters  of  the  trade,  and, 
as  above  mentioned,  heavy  white  substances  are  often  in- 
tentionally incorporated  with  skin  glue,  as  well  as  bone 


150  GLUE,    GELATINE,    CEMENTS,    PASTES. 

glue,  to  give  it  the  appearance  of  Russian  glue.  These 
heavy  powders  add  to  the  weight  of  the  product,  though 
when  incorporated  with  it  in  small  quantities  do  not  injure 
its  adhesive  power,  but  large  quantities  render  the  product 
weaker. 

Patent  glue.  This  term  is  applied  to  an  indefinite  num- 
ber of  preparations,  but  particularly  refers  to  a  very  pure 
variety  of  bone  glue  of  a  deep  dark-brown  color  not  showing 
net  marks.  It  is  very  glossy,  and  swells  up  much  in  water. 
To  satisfy  the  demand  for  thick  cakes,  they  must  be  cut 
from  very  concentrated  jelly  to  insure  their  drying. 

Gilder's  glue  is  found  in  commerce  in  very  thin,  pale 
yellow  cakes  tied  up  in  packages  weighing  about  2  Ibs. 
each.  It  is  a  variety  of  skin  glue  bleached  with  chloride  of 
lime,  and  dissolves  with  difficulty  in  water.  The  first  run- 
nings from  the  boiler  are  used  for  its  manufacture. 

A  very  superior  article  of  gilder's  glue  is  obtained  by 
cutting  rabbit  skins  into  fine  shreds  and  boiling  in  water, 
then  turning  the  mixture  into  a  basket  through  which  the 
liquid  passes,  leaving  the  refuse  behind.  About  100 
grammes  (3.52  ozs.)  of  sulphate  of  zinc  and  20  grammes 
(0.705  oz.)  of  alum  are  then  separately  dissolved  in  pure 
boiling  water  and  poured  into  the  first-mentioned  liquid, 
and  the  whole  well  stirred  together  while  hot.  The  mix- 
ture is  then  passed  through  a  sieve  into  a  rectangular  box, 
in  which  the  jelly  remains  twenty-four  hours  in  winter,  or 
forty-eight  in  summer.  The  solid  mass  is  taken  from  the 
box,  cut  into  slices  of  proper  thickness,  and  dried  upon  nets. 

Size  glue  and  parchment  glue  are  manufactured  in  the  same 
manner.  Both  are  skin-glues,  and  can  be  readily  pro- 
duced by  following  the  directions  given  for  the  manufac- 
ture of  skin-glue. 

Paris  glue  is  used  for  sizing.  It  is  brown,  opaque,  and 
almost  always  soft.  Being  very  hygroscopic,  and  impart- 
ing a  suitable  flexibility  to  the  felt,  it  is  better  adapted  for 
hatter's  use  than  any  other  variety.  For  its  manufacture 


DIFFERENT    VARIETIES    OF    GLUE.  151 

only  the  generative  organs,  or  the  thick  tendons  of  the  legs 
of  cattle  and  horses,  are  used,  or  other  waste  and  fleshy 
parts,  and  substances  mixed  with  small  bones,  which,  if 
thoroughly  cleansed,  might  yield  a  good  quality  of  glue, 
but  are  intentionally  transformed  by  too  long-continued 
boiling,  whereby  the  gelatinous  solution  is  largely  deprived 
of  its  adhesive  power,  and  yields  a  hygroscopic  product. 

Liquid  Glues.  These  are  chiefly  combinations  of  glue 
with  some  ingredients  added  to  destroy  the  gelatinizing 
property  and  yet  not  impair  its  adhesiveness.  They  remain 
for  a  long  time  clear  and  syrupy,  and  are  used  for  a  variety 
of  purposes.  Below  are  given  a  few  receipts  for  such  glues. 

1.  Dissolve  38  parts  of  glue  in  small  pieces  in  100  parts 
of  acetic  acid.     Solution  is  promoted  by  exposing  the  ves- 
sel to  the  sun  or  placing  it  in  hot  water. 

2.  Dissolve  50  parts  of  light-colored  glue  in  50  parts  by 
weight  of  hot  water,  in  which  14  parts  of  fused  magnesium 
chloride    have   been  dissolved.     The  solution  on   cooling 
does  not  gelatinize,  but  remains  syrupy,  the  density  vary- 
ing according  to  the  quantity  of  water  used.     In  the  prepa- 
ration of  printing  inks  it  can  be  used  as  a  substitute  for  gum. 

3.  Dilute   10   parts  of  strong  phosphoric  acid  with  an 
equal  weight  of  water,  and  then  gradually  add  4  parts  of 
ammonium  carbonate  in  the  dry  state.     When  the  efferves- 
cence has  subsided,  add  a  further  5  parts  of  water  and  warm 
on  the  water-bath  or  steam-chest  to  158°  F.     Now  add  20 
to  40  parts  of  glue,  according  to  the  consistency  required, 
and  stir  until  all  is  dissolved.     Cool. 

4.  Dissolve  20  parts  of  glue  in  an  equal  weight  of  hot 
water,  then  cautiously  pour  in,  stirring  constantly,  4  parts 
of  strong  nitric  acid,  warm  until  the  nitrous  fumes  have 
been  driven  off,  filter,  if  necessary,  through  fine  shavings, 
and  allow  to  cool. 

5.  Dissolve  3  parts  of  glue  in  small  pieces  in  12  to  15  parts 
of  saccharate  of  lime.     By  heating,  the  glue  dissolves  rap- 
idly and  remains  liquid,  when  cold,  without  loss  of  adhesive 


152  GLUE,    GELATINE,    CEMENTS,    PASTES. 

power.  Any  desirable  consistency  can  be  secured  by  vary- 
ing the  amount  of  saccharate  of  lime.  Thick  glue  retains 
its  muddy  color,  while  a  thin  solution  becomes  clear  on 
standing. 

The  saccharate  of  lime  is  prepared  by  dissolving  1  part 
of  loaf  sugar  in  3  parts  of  water,  and  after  adding  one-fourth 
part  of  the  weight  of  sugar  of  slaked  lime,  heating  the  whole 
to  between  149°  and  185°  F.,  and  allowing  it  to  macerate 
for  several  days,  shaking  it  frequently.  The  solution,  which 
has  the  properties  of  mucilage,  is  then  decanted  from  the 
sediment. 

The  solution  of  the  glue  in  saccharate  of  lime  is  readily 
accomplished,  even  old  gelatine,  which  has  become  insolu- 
ble in  water,  dissolving  without  difficulty.  This  variety  of 
liquid  glue  possesses  great  adhesive  power,  and  admits  of 
many  uses. 

6.  Dissolve  8  parts  of  glue  in  16  parts  of  hot  water,  then 
add  |  to  1  part  of  hydrochloric  acid,  and  1J  parts  of  sul- 
phate of  zinc.  Keep  the  mixture  for  8  hours  at  158°  F., 
then  filter  through  fine  shavings,  and  allow  to  cool. 

Steam,  glue.  Under  this  name  several  varieties  of  liquid 
glue  are  brought  into  commerce.  They  are  prepared  as 
follows : — 

3.  Russian  steam-glue.  100  parts  of  a  good  quality  of 
glue,  100  to  110  parts  of  warm  water,  and  5.5  to  6  parts  of 
commercial  nitric  acid  of  36°  B. 

2.  Pale  steam-glue.     100  parts  of  glue,  200  of  water,  and 
12  of  nitric  acid  of  36°  B. 

3.  Dark  steam-glue.     100  parts  of  glue,  140  of  water,  and 
16  of  nitric  acid  of  36°  B. 

Soak  the  glue  in  cold  water,  then  pour  the  necessary 
quantity  of  warm  water  over  it,  and  heat  gently  on  a  water- 
bath  until  all  the  glue  is  dissolved.  Next  add  gradually 
the  nitric  acid  with  constant  stirring,  and  to  the  Russian 
steam-glue  6  parts  of  finely  pulverized  sulphate  of  lead, 
which  will  impart  to  it  the  white  color. 


DIFFERENT    VARIETIES    OF    GLUE.  153 

Chrome  glue.  This  preparation  is  very  permanent  and 
durable.  To  prepare  it  add  to  a  moderately  concentrated 
solution  of  5  parts  of  glue  1  of  dissolved  acid  chromate  of 
lime,  this  salt  being  considered  better  for  the  purpose  than 
the  bichromate  of  potash  usually  used.  The  glue  thus 
prepared  becomes,  after  exposure  to  the  light,  insoluble  in 
water  in  consequence  of  a  partial  reduction  of  the  chromic 
acid.  This  preparation  can  be  used  for  cementing  glass 
articles,  liable  to  be  exposed  to  boiling  water,  the  treatment 
being  the  ordinary  one  of  applying  -the  glue  to  both  sur- 
faces of  the  fractured  object,  and  then  binding  them  to- 
gether until  dry,  and  exposing  them  for  a  sufficient  length 
of  time  to  the  light,  after  which  boiling  water  will  have  no 
effect  upon  them.  It  is  suggested  that  this  preparation  is 
better  adapted  to  cementing  the  covers  on  glass  slides  than 
any  now  in  use.  The  same  preparation  can  be  applied  for 
making  fabrics  water-proof,  especially  sails,  awnings,  etc., 
where  no  great  flexibility  is  required.  Two  or  three  appli- 
cations of  the  glue,  either  by  immersion  of  the  object  in  it, 
or  by  the  use  of  the  brush,  will  answer  the  purpose.  Roof- 
ing paper  is  also  rendered  impervious,  even  when  exposed 
to  long-continued  rains. 

Glue  for  attaching  leather  to  metal.  A  method  of  affixing 
leather  to  metal,  so  that  it  will  split  before  it  can  be  torn 
off,  consists  in  digesting  a  quantity  of  nutgalls,  reduced  to 
powder,  in  eight  parts  of  distilled  water  for  six  hours,  and 
filtering  it  through  a  cloth  ;  then  dissolving  one  part  by 
weight  of  glue  in  the  same  quantity  of  water,  and  allowing 
it  to  remain  twenty-four  hours.  The  leather  is  moistened 
with  the  decoction  of  nutgalls  and  the  solution  of  glue 
applied  to  the  metal,  previously  roughened  and  heated. 
The  leather  is  then  laid  upon  it,  and  dried  under  pressure. 

Glue  for  leather,  paper,  etc.  The  following  process  affords 
an  unusually  adhesive  paste,  adapted  to  fastening  leather, 
paper,  etc.,  without  the  defects  of  glue,  and  if  preserved 
from  evaporation  in  closed  bottles  will  keep  for  years. 


154  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Cover  4  parts,  by  weight,  of  glue  with  15  parts  of  cold 
water,  and  allow  it  to  soak  for  several  hours ;  then  warm 
moderately  till  the  solution  is  perfectly  clear,  and  dilute  it 
with  65  parts  of  boiling  water,  intimately  stirred  in.  Next 
prepare  a  solution  of  30  parts  of  starch  in  200  of  cold  water, 
so  as  to  form  a  thin  homogeneous  liquid  free  from  lumps, 
and  pour  the  boiling  glue  solution  into  it  with  thorough 
stirring,  and  at  the  same  time  keeping  the  mass  boiling. 

Glue  for  parchment  paper  in  making  sausage  skins.  The 
supply  of  intestines  soon  being  exhausted  by  the  enormous 
quantity  of  pease-sausages  manufactured  for  the  German 
army  during  the  Franco-German  war,  the  necessity  arose 
for  a  substitute.  This  consisted  of  a  tube  of  parchment 
glued  together.  Millions  of  these  tubes  from  Dr.  Jacobsen's 
factory  were  tested  by  the  government,  and  found  to  answer 
the  purpose  admirably.  They  were  even  boiled  for  hours 
without  either  the  glued  seam  or  the  paper  itself  being  in- 
jured by  the  operation.  The  secret  of  the  composition  of 
the  glue  employed  for  fastening  the  parchment  paper  seems 
to  be  well  kept,  but  the  one  given  in  the  following  is  equal 
to  it  in  all  respects,  if  not  indeed  identical :  Add  to  one 
quart  of  a  good  adhesive  solution  of  glue  }  to  1  oz.  of  finely 
powdered  bichromate  of  potash.  Warm  the  mixture  slightly 
on  a  water-bath  when  about  to  use  it,  and  before  applying 
it  moisten  the  parchment  paper.  The  latter,  when  glued 
with  this  preparation,  as  in  the  formation  of  the  small 
cylinders  for  sausages,  must  be  rapidly  dried  on  a  hurdle, 
and  then  exposed  'to  the  light  until  the  yellow  glue  be- 
comes brownish.  The  cylinders  are  then  slowly  boiled  in 
a  sufficient  quantity  of  water  to  which  two  or  three  per 
cent,  of  alum  has  been  added,  until  all  the  chromate  is  dis- 
solved out,  and  they  are  then  washed  in  cold  water  and 
dried,  and  will  look  very  inviting,  especially  if  white  glue 
has  been  used.  A  similar  result  may  be  reached  by  using 
a  concentrated  solution  of  cellulose  in  ammoniacal  oxide  of 
copper.  Thus  if  cylinders  of  unsized  paper  are  formed  with 


DIFFERENT    VARIETIES    OF    GLUE.  155 

this  paste,  and  when  thoroughly  dry  drawn  through  a 
parchmentizing  solution  (a  cooled  mixture  of  2  volumes  of 
fuming  sulphuric  acid  and  1  volume  of  water),  they  will  be 
beautifully  parchmentized,  and  after  the  neutralization  of 
the  acid,  washing,  etc.,  it  will  present  a  striking  resemblance 
to  natural  intestines. 

Tungstic  glue.  This  preparation  offers  an  acceptable  sub- 
stitute for  hard  India  rubber.  It  is  made  by  mixing  a 
thick  solution  of  glue  with  tungstate  of  soda  and  hydro- 
chloric acid,  by  means  of  which  a  compound  of  tungstic 
acid  and  glue  is  precipitated,  which,  at  a  temperature  of 
86°  to  104°  F.,  is  sufficiently  elastic  to  admit  of  being 
drawn  out  into  very  thin  sheets.  On  cooling,  this  mass 
becomes  solid  and  brittle,  and  on  being  heated  is  again  soft 
and  plastic.  It  can  be  used  for  all  purposes  to  which  hard 
rubber  is  adapted./ 

Indestructiblemass  for  the  manufacture  of  ornaments,  toys, 
etc.  A  mass,  which  is  to  have  the  hardness  of  horn,  con- 
sists of  50  parts  of  glue,  35  of  wax  or  rosin,  15  of  glycerine 
and  the  required  quantity  of  a  metallic  oxide,  or  mineral 
color.  A  soft  mass  consists  of  about  50  parts  of  glue,  25  of 
wax  or  rosin,  and  25  of  glycerine.  The  glue  is  melted  in 
the  glycerine  with  the  assistance  of  steam,  and  the  wax  or 
rosin  added.  The  latter  in  melting  mixes  with  the  glue 
and  glycerine,  and  finally  the  mineral  color  is  added.  The 
mass  is  poured  in  a  liquid  state  into  moulds  of  plaster  of 
Paris,  wood,  or  metal.  The  degree  of  hardness  of  the  mass 
is  increased  by  an  addition  of  30  to  35  per  cent,  of  zinc 
white,  or  other  mineral  color,  according  to  the  color  the 
article  is  to  have. 

Compound  for  billiard  balls.  Allow  80  parts  of  Eussian 
glue  and  10  parts  of  Cologne  glue  to  swell  up  in  10  parts 
of  water ;  then  heat  over  a  water-bath,  and  when  dissolved, 
add  5  parts  of  heavy  spar,  4  parts  of  chalk  and  1  part  of 
boiled  linseed  oil.  Of  a  portion  of  the  mass  form  small 
sticks,  dip  them  in  the  remainder,  and  allow  the  adherent 


156  GLUE,    GELATINE,    CEMENTS,    PASTES. 

portion  to  dry,  and  repeat  this  process  until  a  crude  ball 
has  been  formed.  This  is  placed  in  a  dry  room  for  three 
or  four  months,  and  when  thoroughly  dry,  it  is  turned. 
The  finished  ball  is  placed  in  a  bath  of  sulphate  of  alumina 
for  one  hour,  dried,  and  polished  like  an  ivory  ball. 

Coloring  glue.  Common  black  or  dark  glue,  while 
possessing  all  the  adhesive  and  other  essential  qualities  of 
fine  colored  glue,  has  heretofore,  owing  to  its  color,  been 
confined  in  its  use  to  such  purposes  in  the  arts  where  color 
was  not  essential. 

The  object  of  the  following  process,  which  is  the  inven- 
tion of  G.  J.  Lesser,  of  Frankfort,  Germany,  is  to  color  such 
glue  so  that  it  is  both  refined  and  tinted,  and  may  be  used 
for  various  purposes  in  the  arts.  It  is  especially  applicable 
in  the  manufacture  of  sizing  and  finishing  compounds  for 
paper  hangings,  compounds  for  the  manufacture  of  elastic 
rolls,  for  glue  and  size  compounds  for  finishing  yarns, 
textile  fabrics  of  silk,  cotton,  etc.,  for  the  manufacture  of 
calcimines  and  wall-coverings,  for  glue  to  be  used  with 
colored  woods,  and  for  all  other  purposes  where  a  fine, 
strong-colored  glue  is  required. 

For  coloring  common  black  or  dark  glue  take  a  pound 
and  a  half  of  liquid  extract  of  lead  and  mix  it  into  the 
water  in  which  the  glue  has  been  soaked,  as  follows :  Thir- 
teen pounds  of  glue,  sixty -three  and  a  quarter  pounds  of 
water.  Allow  the  glue  to  soak  for  about  twenty-four  hours, 
then  dilute  it  by  a  slow  fire,  and  when  heated  gradually 
pour  in  one  and  a  half  pounds  of  the  extract  of  lead  and 
mix  it  well  together. 

The  extract  of  lead  is  a  well-known  commercial  article, 
and  it  is  well  suited  for  this  purpose ;  but  the  inventor  does 
not  limit  himself  to  this  particular  preparation,  as  there  are 
a  larger  number  of  neutral  and  basic  compounds  of  lead 
that  may  be  so  modified  as  to  produce  results  similar,  if  not 
identical,  with  the  results  obtained  by  the  formula  above 
given.  Gelatine  may  be  treated  instead  of  glue. 


DIFFERENT    VARIETIES    OF    GLUE. 


157 


Compositions  for  printing  rollers.     All  such  compositions 
contain  gelatine  or  glue.     The  following  receipts  are  used  : 


I. 

II. 

III. 

IV. 

V. 

VI. 

VII. 

VIII. 

Glue   

8 

10 

4 

2 

32 

2 

1 

3 

Molasses     .... 

12 

— 

8 

1 

12 

6 

2 

8 

Paris  white    .    .    . 

1 

— 

— 

— 

— 

— 

— 

1 

Sugar   

— 

10 

— 

— 

— 

— 

— 

— 

Glycerin     .... 

— 

12 

— 

— 

56 

— 

— 

— 

Isinglass     .... 

— 

1£  ozs. 

— 

— 

— 

— 

— 

— 

India     rubber      in 
naphtha  ... 

— 

— 

— 

— 

10 

— 

— 

— 

A  patent  roller  composition  is  thus  made :  Gelatine  32 
Ibs.  and  glue  4  Ibs.  are  softened  in  cold  water  and  melted 
in  a  glue  boiler.  To  this  are  added  4  Ibs.  of  glucose,  72  Ibs. 
of  glycerine,  and  1  oz.  of  methylated  spirit.  The  whole  is 
then  digested  for  four  to  six  hours  and  cast  into  rollers. 
This  composition  is  claimed  to  be  unaffected  by  tempera- 
ture, to  retain  its  elasticity,  and  not  to  shrink. 

In  practice  it  is  found  that  all  these  compositions  from 
the  cleansing  and  remelting  become  gradually  sticky  and 
useless.  To  partially  overcome  this  difficulty,  formaldehyde 
is  added  to  the  roller  composition,  which  renders  the  glue 
insoluble  in  water,  and  thus  prolongs  the  life  of  the  roller. 

Size.  This  product  is  simply  an  undried  glue  and  is 
used,  not  for  adhesiveness,  but  as  a  body  for  filling  porous 
surfaces,  such  as  wood  or  plaster,  stiffening  and  weighting 
textile  fabrics,  in  paper  manufacture,  and  as  a  foundation 
for  oil  paints  and  varnishes.  According  to  Thomas  Lam- 
bert, many  firms  who  have  a  good  selling  connection  for 
size,  do  not  go  to  the  expense  of  erecting  clarifying  plant 
and  drying  house  for  treating  the  glue-liquors,  but  prefer 


. 


158  GLUE,    GELATINE,    CEMENTS,    PASTES. 

to  stop  the  process  half  way,  as  it  were,  and  marketing  the 
resulting  product  as  size.  Others,  again,  with  a  complete 
glue  plant  at  hand,  convert  only  a  portion  of  their  liquors 
into  size,  to  meet  trade  demands,  the  bulk  going  for  the 
manufacture  of  glue.  Size  varies  in  quality  to  suit  the 
requirements  of  different  trades.  Cardboard  box-makers 
prefer  a  strong  skin  size,  which  is  manufactured  red  or 
yellow  as  preferred.  A  strong  yellow  size  made  from  bone 
is  used  by  calico-printers,  paper-stainers,  wall-paper  manu- 
facturers, and  in  the  straw-hat  and  carpet  trades. 

In  the  preparation  of  skin-glue,  the  first  and  second 
liquors  are  used  for  that  purpose  ;  the  residual  mass  is  then 
treated  with  water  and  steam,  which  practically  exhausts 
the  gelatinous  matter.  This,  the  third  liquor,  is  used  solely 
for  size.  During  the  boiling,  samples  are  taken  at  intervals, 
cooled,  and  the  condition  of  the  jelly  noted.  The  strength 
is  also  taken  by  the  glue  meter,  which  registers  the  percent- 
age. At  a  strength  of  8  to  10  per  cent,  the  liquor  is  run 
off,  passing  through  a  filter  of  fine  shavings  or  cloth,  to 
remove  any  suspended  matter,  into  a  wooden  vat  fitted 
with  a  steam  coil,  then  heated  with  a  moderate  charge  of 
sulphurous  acid  to  bring  up  the  color,  and  evaporated  to  a 
strength  of  36  to  38  per  cent.,  as  may  be  desired,  and  then 
run  into  casks  to  jelly.  If  skin-glue  is  not  made,  the  three 
runnings  are  used  entirely  for  size. 

An  outline  of  a  simple  process  used  in  an  English  factory 
devoted  to  making  tub-size,  as  given  by  Samuel  Rideal, 
may  be  interesting. 

The  material  is  obtained  from  the  tanyard  ready  limed 
and  freed  from  hair,  and  consists  mainly  of  "  faces "  of 
bullocks  or  cows,  the  noses  being  cut  off  as  food  for  dogs. 
It  is  soaked  again  in  weak  lime  water  and  re-washed,  then 
placed  in  coppers  made  of  wrought-iron  wrelded  in  one 
piece,  and  holding  about  10  to  20  gallons,  enclosed  in  outer 
jackets  of  the  same  material  containing  water  which  is  kept 
well  boiling.  There  are  six  coppers,  about  five  feet  high 


V, 


DIFFERENT    VARIETIES    OF    GLUE.  159 

by  three  feet  in  diameter.  The  charge  of  each  is  about  J 
cwt.  The  material  is  covered  with  water  and  well  stirred 
with  sticks  for  two  hours,  the  scum  and  dross  being  occa- 
sionally skimmed  off  and  thrown  away  as  useless.  At  the 
end  the  size  is  ladled  on  to  sieves,  from  which  it  runs  into 
cooling  vats,  and  is  filled  while  moderately  hot  into  clean 
tubs. 

The  liquor  is  clear  and  of  a  light  brown  color  for  the 
best  XX  quality,  and  darker  for  the  common.  The  coolers 
or  setting-backs  are  of  wood  or  zinc,  and  the  liquid  is  not 
kept  hot  longer  than  it  can  be  helped,  as  it  is  liable  to  turn 
sour. 

Bone-size  is,  according  to  Thomas  Lambert,  prepared  as 
follows :  The  bones  are  first  degreased  by  the  naphtha  pro- 
cess, and  then  passed  through  the  cleanser  direct  into  the 
glue-boilers  and  steamed,  as  in  the  manufacture  of  glue. 
The  resulting  liquors  are  forced  up  to  the  clarifying  vats 
and  partially  bleached  with  a  current  of  sulphurous  acid, 
passing  through  bag-filters  to  the  evaporating  troughs,  and 
concentrated  from  30  to  38  per  cent.,  as  required,  and  then 
jellied  in  casks. 

The  manufacturer  with  no  benzine  or  glue  plant  at  his 
disposal  washes  the  bones  in  a  revolving  drum,  and,  after 
crushing,  they  are  fed  into  a  boiler  and  subjected  to  an 
alternate  current  of  steam  and  water,  the  latter  coming 
from  a  spray  pipe  fixed  at  the  top  of  the  boiler.  The 
liquors  are  generally  drawn  in  two  portions,  having  a 
strength  of  14  to  16  per  cent,  of  glue.  After  separating  the 
fat,  which  is  refined  and  sold  to  the  soap-maker,  the  liquors 
are  run  into  a  large  wooden  vat  about  8x6x4  feet,  fitted 
with  a  steam  coil,  partly  bleached  with  liquid  sulphurous 
acid,  and  then  boiled  down  to  the  required  strength. 

For  a  common  size  the  bones  are  crushed  but  unwashed, 
and  are  fed  direct  into  the  boiler  and  treated  as  above.  The 
liquors  are  not  bleached,  and  boiled  to  a  strength  of  about 
25  per  cent.  glue.  The  composition  of  the  different  grades 
may  be  given  as  follows  : 


160  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Common  size.  25  per  cent,  glue,  75  per  cent,  water,  etc. 

Medium  size.  30  per  cent,  glue,  70  per  cent,  water. 

Best  size.  38  per  cent,  glue,  62  per  cent,  water. 

A  concentrated  size  is  now  prepared  by  many  manufac- 
turers. It  is  a  bone-size,  and  is  sold  at  a  Baume  strength 
at  122°  C. 

No.  1.  15°  Be.  at  122°  C.,  40.5  per  cent.  glue. 

No.  2.  20°  Be.  at  122°  C.,  44.5  per  cent.  glue. 

No.  3.  25°  Be.  at  122°  C.,  49  per  cent.  glue. 

Under  the  name  of  concentrated  size  also  are  sold  a 
series  of  powdered  glues  of  different  qualities.  They  are 
the  off-color  and  twisted  cakes,  sorted  out  in  the  warehouse, 
and  ground  to  a  fine  condition  by  passing  through  a  mill, 
and  their  value  is  based  on  the  quality  of  the  cake  ground. 

Size  rapidly  ferments  and  becomes  sour  and  mouldy 
unless  some  preservative  is  added.  Sulphate  of  zinc  is 
mainly  used  for  this  purpose. 

Bookbinders'  Size. — I.  Water,  2  quarts  ;  powdered  alum, 
1  oz.  ;  Russian  isinglass,  2  ozs. ;  curd  soap,  40  grains.  Sim- 
mer one  hour,  strain  through  linen  or  a  fine  sieve,  and  use 
while  warm. 

II.  Water,    2    gallons ;    best   glue,    1   Ib.  ;    alum,   4  ozs. 
Prepare  and  use  as  above. 

III.  Water,  2  quarts  ;  isinglass,  5  ozs.  ;  alum,  240  grains. 
/     Water-proof  Glue. — Solution  of  glue  by  itself  or  mixed  with 

*  pigments  is  used  in  painting  walls  in  distemper.  A  water- 
proof coat  is  obtained  as  follows :  Boil  1  part  of  powdered 
gall-nuts  and  12  parts  of  water  until  the  mass  is  reduced  to 
two-thirds  of  its  bulk.  Then  strain  through  a  cloth  and 
apply  the  solution  to  the  dry  coat  of  distemper  paint,  the 
latter  becoming  thereby  as  solid  and  insoluble  as  oil-paint. 
The  tannin  of  the  gall-nuts  acting  only  upon  soft  glue,  the 
solution  has  to  be  applied  so  the  lower  layer  of  glue  becomes 
thoroughly  soaked  through. 

To  render  wrapping  paper  waterproof  the  following  glue- 
solution  may  be  used  :  Dissolve  24  parts  of  alum  and  4 


DIFFERENT    VARIETIES    OF    GLUE.  161 

parts  of  white  soap  in  32  parts  of  water  in  one  pot,  and  in 
another  2  parts  of  gum  arabic  and  6  parts  of  glue  in  32 
parts  of  water,  and  mix  the  two  solutions.  Heat  the  mix- 
ture, immerse  the  wrapping  paper  in  it,  and  pass  it  through 
hot  rolls,  or  dry  upon  twine  stretched  in  frames. 

Fabrics  may  be  rendered  waterproof  with  glue  and  tannin. 
The  process  is  based  on  the  fact  that  by  the  action  of  tannin 
or  bichromates,  compounds  insoluble  in  water  are  formed. 
It  is,  however,  of  first  importance  that  both  solutions — 
tannin  and  glue — should  fully  penetrate  the  fabric.  |  If  the 
latter  is  dipped  directly  into  strong  solution  of  glue  and 
then  of  tannin,  the  glue  will  only  become  insoluble  on  the 
outside,  and  that  which  has  penetrated  deeper  into  the 
fibre  will  be  unchanged,  having  been  protected  by  the 
superficial  insoluble  layer.  Hence,  the  treatment  is  com- 
menced with  a  very  weak  solution  of  glue,  prepared  by 
leaving  glue  broken  small  in  hundred  times  its  weight  of 
water  for  twenty-four  hours.  By  that  time  the  glue  will 
have  swelled  up,  and  the  whole  is  boiled,  whilst  being  con- 
stantly stirred,  so  as  to  get  a  perfectly  clear  solution  in 
which  the  fabric  is  boiled  for  10  to  15  minutes.  This  time 
is  no  more  than  necessary  for  complete  penetration.  The 
fabric  is  then  well  wrung  between  two  rollers  placed  over 
the  glue-bath  so  that  excess  of  solution  runs  back  into  it. 
The  fabric  is  then  hung  up,  and  when  nearly  dry  is  passed 
through  a  tannin  solution.  The  latter  may  be  made  from 
tannin  itself,  or  from  a  tannin  extract,  or  by  boiling  galls 
or  oak  bark  in  water.  The  tannin  solution  can  be  used 
fairly  strong,  as  only  so  much  of  it  is  taken  up  as  corre- 
sponds to  the  glue  present,  and  it  can  be  used  over  again  as 
long  as  it  can  supply  the  tannin  required,  and  can  then  be 
reinforced  with  more  tannin  as  required. 

It  is  not  necessary  for  the  fabric  to  stay  long  in   the 

tannin,  as  it  reacts  quickly  with  the  glue.      The  tanned 

material  is  again  hung  up  to  dry,  and  when  quite  dry  is 

washed  in  plain  water  to  remove  any  excess  of  tannin.  The 

11 


162  GLUE,    GELATINE,    CEMENTS,    PASTES. 

whole  process  from  the  beginning  is  then  twice  repeated. 
After  this  second  repetition  there  is  so  thick  a  layer  of  tan- 
nate  of  gelatine  on  the  fabric  that  the  dry  cloth  has 
acquired  considerable  solidity  and  a  smoothness  which 
recalls  that  of  leather.  The  fabric  is  now  passed  through  a 
stronger  glue  solution,  using  three  or  even  four  parts  of 
glue  per  hundred  of  water,  but  never  exceeding  the  latter 
limit.  After  the  glue-bath  the  fabric  goes  through  the 
tannin  bath,  whereby  it  becomes  quite  thickly  coated  with 
tannate  of  gelatine.  By  repeatedly  treating  with  glue  and 
tannin  alternately,  this  coating  can  be  made  as  thick  as 
desired,  and  finally  masses  are  obtained  in  which  the 
texture  of  the  fabric  is  entirely  hidden,  and  especially  after 
the  fabric  has  been  calendered  under  heavy  pressure  after 
water-proofing.  The  color  acquired  by  goods  thus  water- 
proofed is  a  more  or  less  dark  leather-brown. 

Muratori  and  Landry  treat  the  fabric  with  a  solution 
made  in  three  separate  'operations  : 

1.  Potash  alum  100  Ibs.  dissolved  in  10  gallons  of  boiling 
water. 

2.  In  another  vessel  100  Ibs.  of  glue  are  soaked  in  cold 
water  till  the  glue  has  trebled  in  weight.     The  remaining 
water  is  poured  off,  and  the  glue  liquefied  by  the  applica- 
tion of  heat.     When  the  glue  is  boiling,  5  Ibs.  of  tannin  and 
2  Ibs.  of  soda  water  glass  are  put  in  it. 

3.  The  two  solutions  are  boiled  together,  being  stirred 
constantly. 

When  the  mixture  is  complete,  it  is  allowed  to  cool  to  a 
jelly.  To  water-proof  the  goods  some  of  the  jelly  is  boiled 
with  water  (1  gallon  to  1  lb.,  or  a  little  over)  for  three 
hours,  adding  water  to  compensate  for  evaporation,  so  as  to 
keep  the  volume  of  the  solution  constant,  as  shown  by  tests 
of  its  specific  gravity  with  a  hydrometer.  The  bath  is  then 
allowed  to  cool  to  176°  F.,  and  the  fabric  is  soaked  in  it  for 
half  an  hour  and  then  stretched  out  horizontally  for  six 
hours  to  drain.  The  fabric  must  be  kept  horizontal,  so  that 


DIFFERENT    VARIETIES    OF    GLUE.  163 

the  solution  remains  uniformly  distributed  through  it.  The 
drain  ings  are  collected  to  be  used  over  again.  The  fabric 
is  then  dried  in  the  open  air  or  in  a  drying  room,  still  in 
the  horizontal  position.  If  a  drying  room  is  used  the  tem- 
perature of  it  should  not  exceed  122°  F. 

.Muzmann  and  Krakowitzer  dissolve  10  Ibs.  of  gelatine 
and  10  Ibs.  of  tallow  soap  in  30  gallons  of  boiling  water, 
and  mix  the  solution  in  4  gallons  of  water  in  which  15  Ibs. 
of  alum  have  been  dissolved.  The  whole  is  boiled  for  half 
an  hour,  and  then  allowed  to  cool  to  104°  F.  At  that 
temperature  the  fabric  is  thoroughly  soaked  in  it,  dried, 
rinsed,  again  dried,  and  finally  calendered.  In  this  pro- 
cess the  alum  partially  decomposes  the  soap,  forming  either 
free  fatty  acid  or  an  acid  alumina  soap.  The  gelatine  forms 
an  insoluble  compound  with  the  alum.  The  free  fatty  acid 
or  acid  soap  is  mostly  carried  down  on  the  fibre  by  the  pre- 
cipitate formed  by  the  alum  and  the  .gelatine. 

Glue  for  Joints  in  Leather  Driving  Belts. — Soak  equal  parts 
of  good  hide  glue  and  isinglass  in  water  for  10  hours,  and 
then  boil  with  pure  tannin  till  the  product  becomes  sticky. 
The  surfaces  to  be  cemented  together  should  be  roughened 
and  the  glue  applied  hot. 

According  to  another  method  2  Ibs.  of  best  glue  are  dis- 
solved at  a  moderate  heat  in  3  Ibs.  of  water  and  about  3 
drachms  of  carbolic  acid  stirred  into  the  hot  solution.  The 
mixture  is  poured  into  shallow  iron  pans  to  congeal,  when 
it  is  cut  in  pieces  and  dried  in  the  air.  For  use  the  glue  is 
liquefied  by  adding  a  small  quantity  of  vinegar  and  applied 
with  a  brush  to  the  leather.  The  joint  is  finally  pressed 
between  iron  plates  at  a  temperature  of  about  77°  F. 

Hectograph  Mass. — Soak  a  good  quality  of  glue  for  24 
hours  in  sufficient  cold  water  to  cover  it.  Then  take  the 
swelled  glue  from  the  water  and  melt  it  in  an  enameled  pot 
over  a  moderate  fire.  When  perfectly  liquid  add  the  re- 
quired quantity  of  glycerine  (see  formulas  below)  and  inti- 
mately mix  both  by  continued  stirring. 


164  GLUE,    GELATINE,    CEMENTS,    PASTES. 

The  vessel  containing  the  mixture  should  for  some  time 
be  kept  hot,  so  that  the  mass  remains  thinly  fluid.  The 
purpose  of  this  is  to  allow  the  air-bubbles  formed  by  stirring 
to  rise  to  the  surface.  If  any  scum  is  formed  on  the  sur- 
face, remove  it  carefully  with  a  shallow  spoon.  The  com- 
position is  then  ready  to  be  poured  into  the  vessel  intended 
for  its  reception,  which  may  be  made  especially  for  the 
purpose,  or  a  shallow  baking  pan  of  tin  may  be  used. 
When  the  pan  is  filled  with  the  composition  place  it  per- 
fectly level  in  a  cool  place  free  from  dust  and  allow  to 
remain  at  least  for  several  hours. 

Formulas  for  Hectograph  Masses. — I.  Gilder's  glue,  100 
parts;  glycerine  of  28°  Be'.,  500. 

The  glue  is  allowed  to  swell  in  water,  as  described  above, 
then  melted,  mixed  with  the  glycerine,  and  evaporated  to 
the  required  consistency. 

II.  Gilder's  glue,  100  parts;  glycerine  of  28°  Be.,  400; 
wAter,  200. 


CHAPTER  IX. 

MANUFACTURE  OF  GELATINE,  AND  PKODUCTS  PREPARED 

FROM  IT. 

GELATINE,  like  glue,  is  produced  from  hides  and  skinsr 
and  bones.  It  is  distinguished  by  its  purity,  has  a  slight 
yellowish  tint,  and  is  very  hard  and  elastic.  In  cold  water 
it  softens,  swells  up,  becomes  opaque,  but  does  not  dissolve. 
In  hot  water  it  dissolves  completely,  and  on  cooling  for 
several  hours,  an  almost  colorless,  transparent  and  very 
firm  jelly  results.  This  property  of  becoming  jellied  is  in 
part  lost  if  the  solution  is  for  some  time  exposed  to  a  tem- 
perature higher  than  212°  F. 

The  chemical  constitution  of  gelatine  is  entirely  changed 
by  concentrated  sulphuric  or  nitric  acid.  Concentrated 
acetic  acid,  on  the  other  hand,  renders  softened  gelatine 
transparent,  and  then  dissolves  it ;  the  solution  does  not  be- 
come viscid,  but  preserves  its  adhesive  property.  Dilute 
acids  have  no  appreciable  effect  either  on  the  coagulating 
or  the  adhesive  power. 

Tannin  is  a  valuable  and  delicate  test  of  the  presence  of 
gelatine.  When  added  to  a  solution  containing  only 
sTnnrth  part  of  gelatine,  nebulosity  is  immediately  apparent. 
When  more  concentrated  gelatinous  liquors  are  treated  with 
tincture  or  infusion  of  nut  gall,  a  dense,  white,  caseous  sub- 
sidence occurs  which,  on  desiccation,  becomes  brownish- 
yellow,  agglutinates,  and  forms  a  hard,  brittle  mass  easily 
reduced  to  powder. 

Gelatine  is  much  used  for  culinary  and  medicinal  pur- 
poses, and  for  fining  beer,  wine  and  other  liquids.  Con- 
sidered medicinally,  it  is  emollient  and  demulcent,  and  for 
this  end  is  dissolved  in  water  or  milk,  and  rendered  pala- 

(165) 


166  GLUE,    GELATINE,    CEMENTS,    PASTES. 

table  by  the  addition  of  acid  and  sugar.  In  pharmacy,  it 
is  used  for  the  formation  of  capsules  intended  to  conceal  the 
nauseous  odor  and  taste  of  medicinal  preparations  inclosed 
in  them.  It  is  likewise  employed  for  coating  pills. 

SKIN    GELATINE. 

But  few  changes  have  been  made  in  the  process  of  manu- 
facturing skin  gelatine  since  the  method  introduced  and 
patented,  in  1839,  by  George  Nelson.  This  patent  relates 
to  the  preparation  of  a  transparent  gelatine  from  waste  of 
calf  skins,  and  of  an  inferior  variety  from  other  skins  freed 
from  hair,  wool,  and  fleshy  and  fatty  matters.  The  mode 
of  procedure  is  the  same  in  both  cases,  and  is  as  follows : 
The  cuttings  being  washed  are  macerated  in  solution  of 
caustic  soda  or  caustic  potash  at  a  temperature  of  60°  F., 
until  they  are  partially  softened.  Ten  days  is  the  average 
period  required  to  effect  this.  They  are  then  placed  in 
closed  vessels  and  permitted  to  remain  until  a  thorough 
softening  is  effected.  They  are  now  washed  in  a  revolving 
cylinder,  through  which  a  current  of  water  passes  to  free 
them  from  adhering  alkali ;  exposed  in  a  well-closed  cham- 
ber to  the  action  of  sulphurous  acid,  and  finally  submitted  to 
pressure  to  remove  the  adhering  water.  The  softened  mass 
bleached  by  sulphurous  acid  is  then  placed  in  a  suitable 
vessel  and  subjected  to  the  action  of  steam  until  it  is,  as 
far  as  possible,  dissolved.  The  liquor  is  then  strained  and 
set  aside  at  a  temperature  of  100°  to  120°  F.  for  the  im- 
purities which  may  have  remained  to  subside.  The  clari- 
fied solution  is  poured  upon  slabs  of  slate  or  marble  to  the 
depth  of  about  half  an  inch  and  allowed  to  remain  there  till 
sufficiently  solidified,  when  it  is  cut,  and  washed  to  remove 
all  traces  of  acid.  It  is  subsequently  redissolved  by  means 
of  a  steam  bath  at  a  temperature  of  95°  F.,  finally  again 
solidified,  and  dried  by  exposure  to  dry  air  upon  nets. 

Messrs.  J.  and  G.  Cox,  of  Edinburgh,  patented  in  1844,  a 
process  by  which  a  perfectly  pure  substance,  superior  to 


MANUFACTURE    OF    GELATINE.  167 

that  prepared  from  isinglass  is  obtained.  Shoulders  and 
cheeks  of  ox-hides  are  preferred  by  the  patentees.  They 
are  thoroughly  cleansed  in  water,  after  which  they  are  cut 
into  pieces  by  a  machine  similar  to  that  used  for  cutting 
straw,  and  then  subjected  to  the  action  of  a  paper-maker's 
pulp-mill.  By  this  process  the  gelatinous  fibre  is  well 
washed  and  cleansed,  as  a  stream  of  water  flows  through 
the  mill  during  the  whole  operation,  carrying  off  all  the 
impurities.  The  comminuted  material  is  next  pressed  be- 
tween rolls,  mixed  with  fresh  water,  sufficient  to  effect  its 
solution,  and  heated  to  a  temperature  varying  from  150°  to 
212°  F.  The  resulting  gelatine-solution  is  then  allowed  to 
cool  to  150°  F.,  and  mixed  with  fresh  bullock's  blood — 1 
part  of  the  latter  to  700  parts  of  solution.  At  a  somewhat 
increased  temperature  the  albumen  of  the  blood  coagulates 
and  rises  in  the  form  of  foam  to  the  surface,  or  subsides  in 
the  shape  of  flakes,  carrying  with  it  the  impurities,  and 
thus  clarifying  the  liquor.  The  latter  is  allowed  to  stand 
for  some  time,  when  it  is  poured  upon  stone  slabs  and 
allowed  to  solidify. 

G.  P.  Swinborne's  improved  patented  process  for  the 
preparation  of  gelatine  from  hides,  skins  and  glue  pieces, 
relates  mainly  to  the  cleansing  of  the  raw  material.  The 
latter  is  reduced  by  means  of  suitable  instruments  to  shav- 
ings or  slices,  and  soaked  in  cold  water,  which  is  drained 
off  and  replaced  by  fresh  water  three  times  a  day,  until  no 
odor  or  taste  is  perceptible.  The  shavings  are  then  heated 
with  water,  not  above  boiling,  strained  through  filter  cloths, 
and  the  liquor  is  then  run  on  to  slate  or  other  material 
to  dry. 

The  modern  process  of  preparing  skin  gelatine  is,  accord- 
ing to  Thomas  Lambert,  carried  out  as  follows :  The  first 
treatment  the  cleansed  skins  undergo  is  the  "steeping" 
process  with  caustic  soda  or  milk  of  li^e.  In  some  fac- 
tories a  mixture  of  caustic  (slaked)  lime  and  soda  ash  is 
used,  in  the  proportion  of  6  Ibs.  soda  ash  and  6  Ibs.  slaked 


168  GLUE,    GELATINE,    CEMENTS,    PASTES. 

lime  to  every  hundred-weight  of  skins  treated,  the  chemical 
change  being  that  the  whole  of  the  carbonate  of  soda  (soda 
ash)  is  converted  into  caustic  soda  by  its  equivalent  of 
caustic  lime,  the  excess  of  the  latter  remaining  as  such. 
The  equation  representing  this  is — 

Na2C03     +     CaH202  2NaHO     +     CaC03 

Soda  ash.  Caustic  lime.          Caustic  soda.     Carbonate  of  lime. 

This  steeping  is  conducted  in  large  wooden  vats,  each 
having  a  length  of  12  feet,  width  8  feet,  and  depth  3  feet, 
and  fixed  with  a  slight  gradient  to  the  overflow,  which  is 
placed  at  the  most  convenient  corner  of  the  vat  and  pro- 
tected by  perforated  boards.  The  skins  in  the  vat  are 
nearly  covered  with  water,  and  then  the  solution  of  caustic 
soda,  or  the  slaked  lime  mixed  in  water  to  a  cream,  is 
sprayed  equally  over  the  mass,  the  whole  being  intimately 
mixed  with  long  stirring  poles.  The  water  is  renewed 
twice  during  a  period  of  12  days,  the  time  allowed  for  the 
skins  to  soak.  They  are  now  removed  to  a  chamber,  in 
which  a  moderate  increase  of  heat  facilitates  the  saponifica- 
tion  of  the  fat  and  the  dissolving  of  the  fleshy  matter.  The 
chamber  is  a  brick  building,  with  a  cemented  floor,  on 
which  the  skins  are  spread  to  a  uniform  depth  of  about  six 
inches  and  is  heated  by  steam  pipes  running  round  the  build- 
ing. At  a  temperature  of  about  70°  F.  the  skins  are  ex- 
posed two  or  three  days,  with  frequent  turning.  They  are 
now  transferred  to  the  washing  machine  and  washed  until 
the  effluent  is  practically  free  of  soda  or  lime.  The  skins 
then  undergo  a  bleaching  process  to  whiten,  and  thus  de- 
stroy any  injurious  coloring  matter.  For  this  purpose  the 
washed  skins  are  removed  to  a  number  of  vats  fitted  with 
folding  covers,  and  treated  to  a  solution  of  sulphurous  acid 
of  J°  Twaddell  strength  for  24  hours,  each  vat  being  well 
stirred  at  internals  to  allow  the  "  bleach"  to  permeate 
equally  the  mass. 

In  some  factories  this  process  is  carried  out  with  dry  sul- 


MANUFACTURE    OF    GELATINE.  169 

phuroua  acid,  the  gas  being  generated  in  a  sulphur  burner 
and,  after  washing,  passed  into  a  chamber  containing  the 
skins.  The  vats  are  now  drained,  then  filled  up  with 
water,  well  stirred,  and  the  water  run  off.  This  is  repeated 
until  the  effluent  is  practically  free  of  any  sulphurous  smell, 
and  the  work  of  dissolving  the  gelatine  is  proceeded  with. 
The  digesting  of  the  skins  is  carried  on  in  stoutly  built,  cir- 
cular wooden  vats,  each  having  a  size,  generally  of  4  feet  6 
inches  diameter  and  6  feet  deep,  and  fitted  with  2J  inch 
copper  steam  coil.  The  vats  are  provided  with  a  double 
wooden  bottom  to  divide  the  heat.  They  are  arranged  on 
the  first  floor  of  the  building,  the  liquors  running  through 
a  shallow  filter  of  fine  copper  gauze  to  the  clarifying  vats 
beneath.  The  skins  are  raised  by  an  elevator  and  fed  direct 
into  the  vats  by  suitably-arranged  troughs,  then  covered 
with  water,  and  steam  is  sent  through  the  coils.  The  tem- 
perature is  frequently  taken  by  the  thermometer  and  should 
never  exceed  177°  F.  During  the  digestion,  any  unsapon- 
ified  fat  and  dirt  comes  to  the  surface  as  a  scum,  and  is  care- 
fully skimmed  off  from  time  to  time.  Samples  are  also 
drawn  of  the  liquors,  cooled,  and  the  appearance  and 
strength  of  the  jelly  noted.  After  five  to  six  hours'  heating, 
the  first  liquors  are  run  off  to  the  clarifying  vats,  at  a 
strength  of  about  17  per  cent,  gelatine. 

The  vats  are  refilled  with  water,  and  a  second  digestion 
made,  the  liquor  running  to  the  clarifying  vats  at  a  strength 
of  12  per  cent.  In  the  third  digestion  the  temperature  is 
raised  a  few  degrees  to  practically  exhaust  the  gelatinous 
matter,  and  can  either  be  clarified  to  form  an  inferior  gela- 
tine, or  concentrated  for  size.  The  exhausted  matter  is  taken 
to  the  manure-shed  for  mixing  purposes.  The  clarifying  of 
the  first  and  second  liquors — and  if  used  for  gelatine  the 
third  liquor — is  done  separately  in  the  clarifying  vats.  The 
clearing  agent  used  is  alum,  to  the  extent  of  J  per  cent.,  or 
a  little  blood  diluted  with  water ;  both  are  mixed  with  a 
small  portion  of  the  hot  liquors  in  a  bucket,  and  then  well 


170  GLUE,    GELATINE,    CEMENTS,    PASTES. 

stirred  in  the  vats.  The  liquors  are  raised  to  177°  F.  to 
coagulate  the  impurities,  and  then  lowered  to  149°  F.  and 
allowed  to  stand  for  two  hours.  During  this  time  the 
coagulated  matter  rises  to  the  surface,  and  is  skimmed  off. 
On  leaving  the  vats,  the  liquors  are  filtered  through  fine 
copper  gauze  into  a  receiver  from  which  is  fed  the  vacuum 
pan. 

Gelatinous  liquors  being  peculiarly  sensitive,  especially 
as  regards  color,  to  high  temperatures,  it  is  found  advisable 
to  evaporate  them  in  vacuo ;  and  this  method  is  adopted 
by  all  continental  makers.  The  three  grades  of  the  liquors, 
concentrated  to  the  required  strength,  are  run  on  to  squares 
of  glass,  4'  x  4',  fixed  in  a  wood  framing,  to  a  depth  of  J 
inch  for  cake  and  J  inch  for  leaf  gelatine,  then  placed 
perfectly  level  on  racks  for  jellying.  In  24  hours  the  jelly 
is  firm,  and  can  be  easily  cut  to  the  desired  size  of  cake  or 
leaf  wanted.  A  very  fine  gelatine  is  produced  by  cutting 
the  jelly  into  small  pieces,  washing  well  with  cold  water, 
and  remelting  at  a  temperature  of  176°  F.,  and  poured 
again  on  the  glasses  for  jellying. 

The  drying  is  carried  on  by  exposing  the  cut  cakes,  on 
nets  fixed  to  a  framework  of  wood,  to  a  rapid  current  of  dry 
air  in  the  tunnels,  as  described  in  the  drying  of  glue. 

BONE    GELATINE. 

The  materials  used  for  this  purpose  should  be  of  the  best 
description,  the  most  suitable  bones  being  calves'  feet,  waste 
of  turners  and  button  makers,  the  bony  cores  of  the  horns 
of  the  ox  and  cow.  Such  bones  do  not  require  comminution, 
but  if  large  bones  of  oxen,  horses,  etc.,  are  to  be  used,  it  is 
recommended  to  break  them  as  small  as  possible  by  means 
of  a  wooden  mallet,  and  to  avoid  the  use  of  iron  stampers, 
as  the  bones  become  heated  by  the  heavy  blows  and  friction 
to  which  they  are  subjected  during  the  process,  and  acquire 
an  empyreumatic  odor  which  is  retained  by  the  gelatine. 

The  next  step  in  the  process  is  the  solution  of  the  glue 


MANUFACTURE    OF    GELATINE. 


171 


cartilage.  This  was  formerly  effected  by  the  use  of  steam 
and  water.  The  crushed  bones  were  placed  in  a  wire 
basket  or  cage  and  this  inserted  in  a  small  cast-iron  cylin- 
der and  steam  introduced.  The  apparatus  is  connected 
with  a  steam  boiler,  and  provided  with  an  air-tight  lid,  and 
a  pipe  and  a  rose  connected  with  a  water  reservoir  for  pour- 
ing water  over  the  bones  in  order  to  promote  the  solution 
of  the  glue  cartilage.  But  this  process  is  very  slow,  20 
hours  being  required  without  completely  exhausting  the 
bones. 

The  resulting  gelatinous  liquor  is  drawn  off  every  hour, 
the  first  run,  which  contains  the  dirt  and  grease,  being, 
of  course,  kept  separate  from  the  rest. 

As  will  be  readily  understood  this  process  consumes 
much  fuel,  and  leaves  a  residue  which,  though  not  com- 
pletely exhausted,  cannot  be  further  utilized  for  the  pre- 
paration of  gelatine.  In  fact  the  entire  process  is  obsolete, 

FIG.  59. 


but  as  it  is  still  in  use  in  some  localities,  a  description  is 
here  given,  for  the  sake  of  completeness,  of  the  apparatus 
and  improved  manner  of  manufacture  employed  in  the 
factory  of  D.  J.  Briers,  which  is  well  known  for  the  beauti- 
ful product  turned  out. 

Fig.  59  shows  a  longitudinal  section  of  the  entire  ap- 
paratus. 

Fig.  60  is  the  horizontal  section  of  the  boiler. 


172 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


a,  is  the  cylindrical  boiler  6  meters  (19.68  feet)  long,  and 
2  meters  (6.56  feet)  in  diameter.      It  is  made  of  strong 
boiler  plate  doubly  riveted,  and  capable  of  resisting  a  pres- 
sure of  six  or  seven  atmospheres. 

b,  is  the  manhole.     It  is  closed  by  an  oval  lid  secured 
by  two  iron  rods  and  two  bolts,  so  that  after  placing  the  lid 
in  position,  the  boiler  is  hermetically  closed  by  tightening 
the  nuts  upon  the  bolts. 

c,  is  a  cast-iron  fork  with  two  safety  valves  with  levers 
graduated  from  1  to  100  atmospheric  degrees. 

FIG.  60. 


d  is  a  float  upon  the  surface  of  the  water,  and  provided 
with  a  wheel  graduated  from  Nos.  1  to  6.  Its  object  is  to 
indicate  during  the  operation  how  much  water  is  lost  and 
how  much  remains  in  the  boiler.  Care  must  be  had  not 
to  allow  the  indicator  of  the  wheel  to  get  below  No.  1.  This 
figure  indicates  that  the  water  has  reached  the  highest  point 
in  the  boiler  exposed  to  the  fire,  which  is  consequently  the 
lowest  point  which  the  water  can  be  allowed  to  reach.  On 
the  other  hand  the  indicator  must  not  move  above  No.  6,  as 
the  water  when  standing  too  high  in  the  boiler  and  too 
close  to  the  pipes  conducting  the  steam  into  the  various 


MANUFACTURE    OF    GELATINE.  173 

apparatuses  might  mix  with  the  steam  and  spoil  the  opera- 
tion carried  on  in  the  drum,  e,  Fig.  60. 

/,  Fig  60,  is  a  manometer,  which  indicates  the  degrees  of 
pressure  exerted  by  the  steam  in  the  interior  of  the  boiler. 
It  consists  of  a  wrought-iron  pipe  bent  double,  and  is  filled 
with  mercury  1.22  meter  (4.002  feet)  high  counted  from  its 
base.  One  end  of  the  pipe  communicates  with  the  boiler, 
while  the  other  end  is  provided  with  a  small  brass  wheel. 
Upon  the  latter  is  a  thread  of  twisted  silk,  to  the  end  of 
which  is  suspended  an  iron  cylinder  of  somewhat  smaller 
circumference  than  the  bore  of  the  pipe,  so  that  it  can  move 
up  and  down  in  it  without  friction.  This  cylinder  rests 
always  upon  the  mercury.  To  the  other  end  of  the  thread 
is  fastened  an  indicator  of  somewhat  less  weight  than  the 
cylinder,  which,  by  sliding  in  a  groove  in  a  graduated 
board  placed  alongside  the  pipe,  indicates  the  degrees  of 
steam  pressure. 

g  is  a  cast-iron  pipe  for  heating  the  drying  room,  and 

h  another  cast-iron  pipe  for  heating  the  store-room  for 
the  bones. 

i  is  the  forcing  pump  for  feeding  the  boiler  with  water. 

k  is  a  sheet-iron  reservoir  placed  close  to-  the  end  of  the 
boiler.  It  is  filled  with  water,  which  is  heated  by  the  heat 
lost  in  the  fireplace  in  consequence  of  the  draught,  and  by 
allowing  the  smoke  to  circulate  under  the  reservoir  before 
passing  into  the  chimney.  The  reservoir  communicates 
with  the  forcing-pump  by  means  of  a  pipe  and  stopcock, 
so  as  to  avoid  feeding  the  boiler  with  cold  water. 

I  is  the  fireplace,  consisting  of  the  grate,  door  and  cast- 
iron  frame. 

The  drum,  e,  is  a  spherical  vessel  of  strong  sheet-iron 
doubly  riveted.  It  is  3  meters  (9.84  feet)  in  diameter,  and 
capable  of  resisting  a  pressure  of  six  to  seven  atmospheres. 
It  serves  for  softening  the  bones  with  the  assistance  of  steam 
passed  into  it  from  the  boiler,  a.  It  is  provided  with  a 
manhole  similar  to  that  of  the  boiler. 


174 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


n  is  a  wrought-iron  shaft  passing  horizontally  through 
the  drum  and  revolving  in  the  brasses,  o. 

g,  Fig.  61,  is  a  gearing  with  a  crank,  by  means  of  which 
the  drum  e  is  revolved.  The  power  of  the  gearing  must  be 
so  calculated  that  one  man  can  turn  the  wheels  when  the 
drum  is  filled  with  water. 

FIG.  61. 


r  is  a  false  bottom  perforated  in  its  entire  length  with 
holes  12  millimeters  (0.47  inch)  in  diameter,  and  is  placed 
about  15  centimeters  (5.9  inches)  above  the  true  bottom  of 
the  drum.  It  consists  of  two  pieces,  and  is  secured  by  two 
nuts,  so  that  it  can  be  easily  removed  and  replaced.  Its 
object  is  to  prevent  the  bones  from  clogging  up  the  pipe  s, 
and  the  cocks  t,  u. 

a,  a,  Fig.  61,  are  angular  iron  points  inside  of  the  drum 
e.  Their  object  is  to  facilitate  the  shifting  of  the  bones 
when  the  drum  is  revolving. 

x,  Fig.  59,  is  a  cock  near  the  manhole.  It  is  opened 
about  2  millimeters  (0.079  inch)  during  the  operation  in 
the  drum.  It  serves  also  for  the  escape  of  the  steam  from 
the  drum  when  the  operation  is  finished. 

The  cocks  t,  u,  placed  in  the  lower  part  of  the  drum, 
serve  for  the  escape  of  steam  condensed  during  the  opera- 
tion. 

The  steam  pipe  p,  Fig.  59,  conducts  the  steam  from  the 
vessel  a  into  the  drum  e. 

y,  Fig.  59,  is  a  cock  graduated  into  eight  equal  parts  and 


MANUFACTURE    OF    GELATINE. 


175 


placed  on  the  steam  pipe  p,  to  conduct  the  steam  from  the 
box  2,  into  the  stuffing  box  a',  and  from  there  into  the  pipe 
3,  then  under  the  false  bottom  r,  into  the  drum  e. 

The  lid  of  the  cast-iron  box  2,  is  provided  with  a  safety 
valve  loaded  with  a  weight  corresponding  to  the  pressure  of 
one  atmosphere. 

The  wooden  vessel  or  box  d,  the  ground-plan  of  which  is 
shown  in  Fig.  62,  serves  for  boiling  the  comminuted  bones 
in  order  to  extract  the  jelly.  This  box  consists  of  the  fol- 
lowing parts  : — 

n,  are  cast-iron  steam  pipes  occupying  the  entire  surface 
of  the  box,  being  placed  at  equal  distances  from  each  other, 
and  connected  on  their  ends  by  semi-circular  pieces.  The 
steam,  which  is  allowed  to  circulate  in  the  pipes  in  order  to 

FIG.  62. 


boil  the  liquid,  enters  through  one  of  the  ends  which  rises 
up  vertically  and  is  connected  with  the  cock  h',  Fig.  59. 
The  other  end  is  secured  to  the  inner  side  of  the  box,  which 
is  perforated  for  the  admittance  of  the  cock  of.  Upon  the 
steam  pipes  lies  a  wooden  frame-work  with  linen  nailed 
upon  it,  the  object  of  which  is  to  prevent  the  comminuted 
bone  substance  from  falling  under  the  pipes.  The  frame 
must,  of  course,  fit  closely  into  the  box. 

The  cock  li'  graduated  in  eight  equal  parts  serves  to 
admit  steam  irito  the  pipes  n',  and  is  opened  either  entirely 
or  half,  or  one-quarter,  or  one-eighth,  according  to  the 
stronger  or  gentler  ebullition  to  be  produced. 

To  prevent  the  steam   from  becoming  stagnant   in  the 


176 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


steam  pipes  nf,  a  small  jet  is  allowed  constantly  to  escape 
through  the  cock  o'  '.  The  latter  serves  also  to  run  off  the 
condensed  steam  when  it  no  longer  possesses  the  heat  re- 
quired to  keep  up  ebullition. 

pf,  Fig.  62,  is  a  cock  in  the  bottom  of  the  box  df  for 
drawing  off  the  gelatinous  solution  from  the  residue.  The 
box  e'j  Fig.  62,  a  ground-plan  of  which  is  shown  in  Fig.  63, 
serves  for  evaporating  the  gelatinous  solution,  which  is 
effected  by  circulating  steam  through  several  tubular  pieces 
of  cast-iron  which  form  the  bottom  of  the  box  and  are  con- 
nected in  a  similar  manner  as  the  pipes  in  the  box  df. 

The  cock  i  is  graduated  and  similar  to  hf. 


FIG.  63. 


<D= 

r 


The  cock  r',  Fig.  63,  is  similar  to  o',  Figs.  59  and  62. 

s',  Fig.  63,  is  a  cock  for  drawing  off  the  evaporated 
gelatinous  solution. 

The  wooden  box  /',  Fig.  59,  a  ground-plan  of  which  is 
shown  in  Fig.  64,  serves  for  the  reception  and  settling  of 
the  evaporated  gelatinous  solution.  Its  bottom  is  con- 
structed in  a  manner  similar  to  that  of  the  box  ef. 

The  cock  n',  which  is  placed  14  millimeters  (0.55  inch) 


FIG.  64. 


T 


above  the  bottom  of  the  box,  serves  for  running  the  gela- 
tinous solution  into  the  wooden  cooling-boxes. 


MANUFACTURE    OF    GELATINE.  177 

The  bones  as  received  in  the  factory  are  sorted  by  throw- 
ing out  the  spongy  material,  etc.  They  are  then  steeped  in 
lime-water  for  a  few  days  to  free  them  from  adhering  par- 
ticles of  flesh,  after  which  they  are  dried  and  stored  away 
for  future  use. 

The  boiler  a,  is  filled  two-thirds  with  water,  and  heated 
u-ntil  the  manometer  indicates  a  pressure  of  30°.  In  the 
meanwhile  the  drum  e,  is  filled  seven-eighths  with  perfectly 
dry  bones,  and  steam  is  then  admitted  from  the  boiler  a, 
through  the  graduated  cock  y.  The  fact  that  the  bones  in 
the  drum  are  exposed  to  the  proper  temperature  of  250°  F. 
is  recognized  by  the  thermometer  6',  placed  between  the 
cock  and  the  drum. 

To  prevent  the  stagnation  of  the  steam  in  the  drum,  a 
small  jet  of  it  is  allowed  constantly  during  the  operation  to 
escape  through  the  cock  x.  The  cock  must  not  be  opened 
wider  than  is  necessary  to  keep  the  temperature  at  250°  F. 
By  opening  it  wider,  this  degree  would  be  exceeded,  and 
the  gelatine-yielding  substance  would,  in  consequence, 
undergo  alteration.  A  quarter  of  an  hour  after  admitting 
the  steam  into  the  drum,  the  cock  t,  is  opened,  and  again 
closed  after  allowing  a  small  portion  of  the  condensed  steam 
to  escape  to  the  cock  u,  and,  through  this,  into  a  box.  This 
operation  is  repeated  every  quarter  of  an  hour. 

To  change  the  position  of  the  bones,  the  drum  is  revolved 
twice  every  half  hour,  by  means  of  the  gearing  q,  of  course 
closing  the  cock  x  during  the  operation. 

By  carefully  following  the  above  rules,  the  bones  will  be 
thoroughly  reduced  in  four  hours.  If,  for  instance,  steam 
has  been  introduced  into  the  drum  at  5  o'clock  a.  m.  the 
operation  will  be  finished  at  9  a.  m.  The  cock  y,  is  then 
closed,  and  the  steam  allowed  to  escape  through  the  cock  x. 
After  the  escape  of  the  steam,  the  drum  is  emptied,  by  re- 
moving the  lid  and  turning  it  upside  down.  It  is  then  re- 
filled with  entirely  dry  bones,  and  the  operation  continued 
in  a  like  manner,  day  and  night,  if  necessary. 
12 


178  GLUE,    GELATINE,    CEMENTS,    PASTES. 

After  the  bones  have  been  taken  from  the  drum,  they  are 
spread  out  under  a  shed,  and,  when  dry,  ground  in  a  suit- 
able mill.  The  resulting  flour,  which  contains  the  jelly- 
yielding  substance,  is  brought  into  the  vessel  df,  which,  in 
the  meanwhile,  has  been  furnished  with  sufficient  water  to 
cover  the  flour  65  centimeters  (25.59  inches)  deep.  The 
mixture  is  boiled  for  three-quarters  of  an  hour,  being  con- 
stantly stirred  to  prevent  the  flour  from  forming  a  heavy 
and  dense  mass  whicli  would  hinder  the  quick  extraction 
of  the  jelly.  Ebullition  is  then  interrupted  by  closing  the 
cock  h,  and  the  fat  floating  on  the  surface  skimmed  off. 
After  allowing  the  gelatinous  solution  to  settle,  it  is  drawn 
off  by  means  of  a  faucet  placed  above  the  level  of  the  flour. 
Thirty  bucketfuls  of  the  gelatinous  solution  are  then  at  once 
poured  into  a  vat  and  mixed  with  the  condensed  steam 
drawn  off  by  means  of  the  cocks  t  u,  during  the  reduction 
of  the  bones  in  the  drum.  After  allowing  the  mixture  to 
cool  to  160°  to  155°  F.,  20  kilogr.  (44  Ibs.)  of  pulverized 
alum  are  added  at  once  and  as  quickly  as  possible.  When 
the  gelatinous  solution  has  become  transparent,  it  is  drawn 
off  into  the  box  e',  and  a  few  bucketfuls  of  hot  water  are 
poured  upon  the  sediment  in  the  vat  in  order  to  extract  the 
remaining  jelly,  which  is  effected  by  thorough  stirring  and 
allowing  to  settle  until  the  water  is  entirely  clear. 

After  disposing  of  the  30  bucketfuls  in  the  manner  men- 
tioned, the  remainder  of  the  gelatinous  solution  is  evapor- 
ated. This  is  accomplished  in  the  box  e',  which  is  filled  8 
centimeters  (3.15  inches)  deep  with  gelatinous  solution,  and 
steam  is  then"  admitted  into  the  tubular  bottom  pieces.  To 
promote  evaporation  and  keep  the  fluid  constantly  in  mo- 
tion, the  cock  i'  is  only  opened  far  enough  to  keep  up 
gentle  ebullition.  During  evaporation  the  solution  should 
be  frequently  stirred  with  an  implement  resembling  a  rake. 
The  nearer  the  required  degree  of  concentration  is  ap- 
proached, the  greater  care  must  be  exercised  to  prevent  the 
solution  from  boiling  too  strongly.  The  proper  degree  of 


MANUFACTURE    OF    GELATINE.  179 

consistency  is  obtained  when  half  a  saucer  full  of  the  solu- 
tion placed  in  a  shady  place  in  the  air  acquires  in  a  short 
time  such  a  consistency  that  when  touched  with  the  finger 
no  impression  remains.  The  cock  i'  is  then  closed,  and  the 
jelly  is  drawn  off  into  the  box  df,  which  contains  the  30 
bucketfuls  of  clarified  jelly,  care  being  had  to  mix  the  two 
solutions  as  quickly  as  possible.  After  evaporating  all  the 
gelatinous  solution  and  mixing  it  in  the  box  df,  the  whole 
is  heated  to  158°  F.,  by  admitting  steam  through  the  cock 
k' ,  care  being  had  not  to  forget  closing  it  as  soon  as  the 
above  temperature  has  been  reached.  The  solution  is  then 
thoroughly  stirred  and  permitted  to  settle  for  three  hours 
to  allow  of  the  precipitation  of  the  lime  salts  decomposed 
by  the  alum.  The  fluid,  which  is  now  perfectly  transpar- 
ent and  of  a  beautiful  dark-yellow  color,  is  then  drawn  off 
into  wooden  cooling  boxes  2  to  2.5  meters  (6.56  to  8.2  feet) 
long,  20  centimeters  (7.87  inches)  wide,  and  16  centimeters 
(6.30  inches)  deep.  The  following  day  the  gelatine  is  cut 
into  leaves  25  centimeters  (9.84  inches)  long  and  12  centi- 
meters (4.72  inches)  wide,  which  are  dried  upon  nets. 
When  quite  dry,  the  drying  process  is  finished  by  bringing 
the  leaves  into  the  drying-room  which  is  heated  by  the  pipe 
g.  (Fig.  59.) 

The  bone  flour  remaining  in  the  box  dr  still  contains 
much  jelly,  which  is  extracted  by  pressure.  This  is  accom- 
plished immediately  after  running  off  the  gelatinous  solu- 
tion into  the  evaporating  vessel.  The  liquid  which  has 
drained  through  the  cloth  frame  previously  mentioned,  is 
drawn  off  by  opening  the  cock  p',  Fig.  62,  while  the  residue 
in  the  box  df  is  placed  in  coarse  bags  and  the  jelly  extracted 
by  subjecting  the  bags  to  strong  pressure  under  an  iron 
sere w -press.  Before  mixing  the  extracted  fluid  with  the 
solution  in  the  evaporating  vessel,  it  is  recommended  to 
allow  it  to  settle,  as  it  is  always  more  or  less  turbid.  The 
residue  remaining  in  the  bags  is  an  excellent  manure. 

The  modern  process  of  preparing  bone  gelatine,  which  is 


180  GLUE,    GELATINE,    CEMENTS,    PASTES. 

now  almost  in  general  use  is  as  follows:  Clean  bones  are 
selected  for  the  purpose,  and  the  operation  commences  with 
the  extraction  of  the  fat  by  means  of  benzine,  though  some 
manufacturers  prefer  carbon  disulphide  as  a  solvent,  be- 
cause it  is  claimed  that  by  reason  of  its  low  boiling-point  it 
does  not  injure  the  gelatine  in  the  same  manner  as  benzine, 
and  besides  it  leaves  no  smell  in  the  degreased  bones.  It 
is  advisable  to  bleach  the  degreased  bones,  spread  out  in 
thin  layers  and  kept  constantly  moist,  by  exposure  to  the 
action  of  air  arid  light.  The  bleached  bones  are  conveyed 
to  large  vats  for  the  purpose  of  extracting  their  mineral 
constituents  by  digestion  with  hydrochloric  acid.  If  the 
gelatine  is  to  be  used  as  an  article  of  food,  or  for  medicinal 
purposes,  only  the  purest  hydrochloric  acid  obtainable 
should  be  used,  while  the  ordinary  article  suffices  for  that 
for  technical  purposes. 

The  vats  are  tilled  three  parts  full  with  bones  and  the 
latter  covered  with  a  solution  of  hydrochloric  acid  of  10  per 
cent,  strength.  Digestion  is  carried  on  until  the  bones 
become  soft,  flexible  and  semi-transparent.  The  acid  water 
is  now  drained  off,  and  a  supply  of  fresh  water  added,  and 
then  discharged.  This  is  repeated  until  the  last  water  is 
entirely  free  of  acid,  which  is  known  by  adding  a  few  drops 
of  silver  nitrate,  the  absence  of  any  white  precipitate  indi- 
cating that  the  water  is  entirely  free  of  acid. 

The  bones  are  now  bleached  in  the  manner  as  described 
under  skin-gelatine,  preferably  with  solution  of  sulphurous 
acid,  the  process  with  gaseous  sulphurous  acid  being  diffi- 
cult to  carry  out  and  considerable  time  is  required  for  the 
gas  to  completely  permeate  the  cartilaginous  mass.  The 
bleached  bones  are  then  conveyed  to  the  boiling  vats  and 
the  resulting  liquors  treated  in  the  same  manner  as  de- 
scribed under  skin-gelatine. 

As  bone-gelatine  solidifies  with  a  larger  content  of  water 
than  the  product  from  skins,  evaporation  of  the  liquors  may 
be  early  interrupted  and  the  resulting  jelly  cut  into  thin 
leaves  which  are  finally  dried. 


MANUFACTURE    OF    GELATINE.  181 

COLORED    GELATINE. 

Cakes  or  leaves  not  entirely  colorless  may  be  utilized  for 
colored  gelatine  which  is  employed  for  various  purposes. 
Coloring  is  effected  by  simply  dissolving  and  distributing 
uniformly  a  suitable  quantity  of  coloring  matter  in  the 
clarified  gelatine  liquor  previous  to  solidifying ;  of  course 
only  water-soluble  coloring  matter  should  be  used. 

Colored  gelatines  are  frequently  used  by  confectioners  and 
in  the  household  in  the  preparation  of  jellies,  and  the  use  of 
poisonous  colors  should  under  all  conditions  be  avoided. 
Sufficient  attention  is  not  paid  to  this,  because  many  of  the 
aniline  colors  which  are  now  so  much  used  for  the  purpose 
are  at  least  open  to  suspicion,  while  others,  especially  picric 
acid,  which  yields  a  beautiful  yellow  color,  are  decidedly 
poisonous. 

The  following  coloring  matters  are  perfectly  harmless  and 
yield  good  results  in  coloring  gelatine  : 

Yellow :  Caramel  or  sugar  color.  A  still  more  beautiful 
yellow  is  obtained  by  the  use  of  an  aqueous  extract  of 
saffron. 

Red  :  Extract  of  cochineal. 

Blue :  Indigo-carmine  solution. 

Green  :  Mixture  of  indigo-carmine  and  caramel. 

Violet :  Mixture  of  extract  of  cochineal  and  indigo-car- 
mine. 

While  gelatine  colored  with  the  above-mentioned  color- 
ing matter  does  not  preseut  such  a  beautiful  appearance  as 
the  product  colored  with  aniline  colors,  it  is  entirely  harm- 
less and  suitable  for  culinary  purposes. 

Leaves  of  gelatine  colored  with  aniline  colors  exhibit 
beautiful  colors  and  are  used  for  many  technical  purposes. 
The  following  colors  may  be  employed  : 

Yellow :  Picric  acid  soluble  in  hot  water. 

Red :  Fuchsine  or  eosine. 

Blue :  Water-soluble  blue. 

Green:  Iodine  green. 


182  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Violet :  Methyl  violet. 

Gelatine  for  Fining  Purposes. 

For  fining  beer,  wine,  etc.,  gelatine  in  leaves  or  in  powder 
is  brought  into  commerce.  For  the  preparation  of  leaves, 
gelatine  particularly  well  dried  is  carefully  melted  over  a 
water-bath  and  then  ladled  into  sheet-metal  moulds,  and 
allowed  slowly  to  solidify. 

The  product  brought  into  commerce  under  the  name  of 
Gelatine  Lainee  which  commands  a  high  price  is  in  many 
cases  nothing  but  thoroughly  purified  bone-glue  of  a  dark 
honey-yellow  to  brown  color. 

Fining  powder  for  wine  and  beer  is  made  by  grinding 
off-color  gelatine  cakes  and  freeing  the  resulting  powder 
from  coarser  pieces  by  sifting.  The  powder  is  white. 

Liquid  fining  gelatine.  This  preparation  consists  of  gela- 
tine-solution suitably  prepared,  and  represents  a  colorless, 
or  at  the  utmost  slightly  opalescent,  product  just  sufficiently 
concentrated  to  remain  liquid. 

Skin-liquors  can  only  be  used  for  the  preparation  of 
liquid  gelatine,  as  bone-liquors  already  gelatinize  when  they 
contain  scarcely  more  than  1  per  cent,  of  glue.  The  skin 
liquors  are  concentrated  so  far  as  to  remain  liquid  at  a 
temperature  of  from  60°  to  68°  F. 

A  product  answering  all  demands  is  obtained  as  follows  : 
A  good  quality  of  gelatine  of  a  pale  color  is  dissolved  in  a 
sufficient  quantity  of  water,  the  solution,  in  case  it  shows  a 
slight  odor,  filtered  through  animal  charcoal,  and  then 
brought  into  bottles.  To  prevent  putrefaction  the  liquid 
gelatine  is  sterilized  as  follows: 

The  filled  bottles  being  placed  in  a  boiler  filled  to  a 
proper  depth  with  water,  the  latter  is  slowly  brought  to 
boiling  which  is  kept  up  for  15  to  20  minutes.  The  bottles 
are  then  closed  with  corks  previously  boiled  in  the  water. 

Preparation  of  Gelatine  from  Ordinary  Glue. 
For  this  purpose  ordinary  pale-colored  glue  is  allowed  to 


MANUFACTURE    OF    GELATINE.  183 

swell  up  for  two  days  in  cold  strong  vinegar.  The  vinegar 
is  then  drained  off  and  the  glue  which  is  now  almost  color- 
less, is  placed  upon  a  sieve  arid  allowed  to  float  in  a  vessel 
rilled  with  water  for  10  to  12  hours.  It  is  then  placed 
upon  a  linen  cloth,  stretched  in  a  room  heated  to  at  the  ut- 
most 68°  F.,  allowed  to  drain  and  dry  to  such  an  extent 
that  on  heating  it  to  between  158°  and  167°  F.,  a  thick 
clear  liquid  is  obtained.  This  liquid  is  carefully  poured 
upon  plates  of  glass  or  marble,  so  as  to  avoid  the  formation 
of  air  bubbles  and  when  solidified  the  leaves  are  removed 
and  completely  dried  in  the  air.  The  product  thus  ob- 
tained being  entirely  tasteless  and  almost  colorless  may  be 
used  in  the  preparation  of  jellies,  as  well  as  for  foils  for 
pictures,  etc. 

Preparation  of  Gelatine  for  Photographic  Printing  and  for 
Photographic  Purposes  in  General. 

Gelatine  suitable  for  this  purpose  should  be  colorless  and 
free  from  all  salts,  since  the  latter  would  exert  a  disturbing 
effect  upon  the  chemical  processes  which  take  place  during 
the  photographic  operation.  For  the  removal  of  the  salts 
the  gelatine  is  treated  as  follows :  Colorless  gelatine  of  the 
best  quality  is  broken  into  small  pieces  and  covered  with 
10  to  12  times  the  quantity  of  water,  the  latter  being 
changed  every  15  to  20  minutes  until  the  last  water  shows 
no  trace  of  lime,  which  is  known  by  adding  to  the  water 
solution  of  oxalate ;  the  absence  of  turbidity  indicates  that 
the  water  is  free  from  lime.  The  white  of  an  egg  is  now 
mixed  with  five  drops  of  ammonia  and  twice  the  volume  of 
distilled  water  and  shaken  to  froth  in  a  bottle.  This  quan- 
tity suffices  for  6  to  8  ozs.  of  gelatine.  The  washed  gelatine 
is  next  melted  in  a  dish  and  mixed  with  the  white  of  egg. 
One  part  of  glacial  acetic  acid  mixed  with  250  parts  of 
water  is  then  added  drop  by  drop,  stirring  constantly  until 
sensitive  litmus  paper  shows  an  acid  reaction.  The  liquid 
is  now  rapidly  brought  to  the  boiling-point,  whilst  stirring 


184  GLUE,    GELATINE,    CEMENTS,    PASTES. 

constantly,  and  then  filtered  in  a  warm  place  to  avoid  gela- 
tinization.  The  gelatine  now  contains  only  the  salts  of  the 
white  of  egg,  some  ammonium  acetate  and  free  acetic  acid. 
For  their  removal  the  solidified  gelatine  is  cut  into  pieces, 
which  are  placed  in  water. 

Gelatine  Capsules  for  Medicinal  Purposes. 

Considerable  use  is  made  of  gelatine  in  medicine.  To 
disguise  the  disagreeable  taste  of  some  medicines  they  are 
either  m'ixed  with  gelatine  solution  or  inclosed  in  gelatine 
capsules.  To  prepare  the  latter,  dissolve  8  parts  of  gelatine, 
2  of  sugar,  and  1  of  gum-arabic  in  8  of  water  in  a  water- 
bath,  and  dip  the  pear-shaped  ends  of  iron  rods  into  the 
lukewarm  solution.  To  facilitate  the  detaching  of  the  gel- 
atine film  from  the  rods,  grease  the  pear-shaped  ends  with 
oil.  The  capsules  are  dried  by  placing  them  in  holes  of  a 
corresponding  size  in  boards.  When  dry  they  are  filled 
with  the  respective  medicine,  and  closed  with  a  drop  of  the 
same  solution. 

Court  Plaster. 

Gelatine  or  isinglass  155  grains,  alcohol  13J  fluid 
drachms,  glycerine  15J  grains.  Water,  tincture  of  benzoin, 
each  a  sufficient  quantity.  Dissolve  the  gelatine  in  a  suffi- 
cient quantity  of  hot  water  to  make  the  solution  weigh  4J 
ozs.  Spread  one-half  of  this  in  successive  layers  by  means 
of  a  brush  upon  taffeta  stretched  upon  a  frame  so  as  to  pre- 
sent a  level  surface,  waiting  after  each  application  until  the 
layer  is  dry.  For  the  first  two  applications  the  gelatine 
solution  should  be  warmed  merely  to  above  its  congealing 
point,  so  that  when  spread  out  it  may  rapidly  solidify 
and  at  the  same  time  adhere  to,  but  not  pass  through  the 
fabric.  Mix  the  second  half  of  the  gelatine  solution  with 
the  alcohol  and  glycerine,  and  apply  it  in  the  same  manner. 
Then  reverse  the  taffeta,  coat  it  on  the  back  with  the  tinct- 
ure of  benzoin  and  allow  it  to  become  perfectly  dry.  The 
tincture  of  benzoin  applied  to  the  reverse  side  leaves  a  thin 


MANUFACTURE    OF    GELATINE.  185 

layer  of  resin  which  in  a  measure  renders  the  plaster  water- 
proof; it  is,  however,  advisable  to  repeat  this  application 
once  or  twice.  The  addition  of  glycerine  to  the  last  portion 
of  the  gelatine  solution  prevents  the  plaster  from  breaking, 
and  preserves  its  flexibility  for  a  long  time.  When  the 
plaster  is  dry  it  is  cut  in  pieces  of  suitable  length  and  pre- 
served in  well-closed  vessels. 

Gelatine  Foils. 

Large  quantities  of  gelatine  foils,  which  are  leaves  of  gel- 
atine about  as  thick  as  a  sheet  of  paper,  are  produced  in 
England  and  France  where  their  manufacture  forms  a  spec- 
ial branch  of  industry.  They  are  either  simply  colored  or 
printed  with  neat  designs  in  gold  or  silver. 

The  fabrication  is  quite  simple.  Cover  pure  gelatine 
with  water,  and  after  swelling  up,  pour  off  the  water  and 
dissolve  the  jelly  over  a  water-bath.  After  allowing  the 
solution  to  cool  somewhat,  add  the  coloring  matter  previously 
dissolved  in  water. 

In  place  of  pure  gelatine,  a  solution  of  ordinary  bone-glue 
may  be  used.  In  order  to  clarify  it  add  0.14  oz.  of  oxalic 
acid  dissolved  in  water  to  every  5.5  Ibs.  of  glue.  To  make 
the  foils  more  flexible  add  also  one-half  pint  of  spirit  of 
wine  and  0.28  oz.  of  rock  candy  or  a  small  quantity  of  gly- 
cerine. 

Aniline  colors  soluble  in  water  are  best  adapted  for  color- 
ing the  foils ;  for  red,  fuchsine,  eosine  or  ponceau,  for  blue, 
blue  de  Parme,  for  green,  aldehyde  green,  for  yellow,  picric 
acid,  and  for  the  various  shades,  mixtures  of  the  above 
colors. 

A  durable  blue  is  also  produced  by  indigo  solution,  yel- 
low, by  decoction  of  saffron,  green,  by  mixing  blue  and 
yellow,  red,  by  a  solution  of  carmine  in  spirit  of  sal  ammo- 
niac, and  violet,  by  mixing  blue  and  carmine. 

The  gelatine  solutions  are  poured  upon  ground-glass 
plates,  previously  polished  with  elutriated  rouge,  and  rubbed 


186  GLUE,    GELATINE,    CEMENTS,    PASTES. 

with  Spanish  chalk.  The  foils  are  so  smooth  upon  the 
glass  side  that  when  dry  they  can  be  detached  without 
much  difficulty.  If  both  sides  are  required  to  be  smooth, 
the  foils  are  dried  between  two  glass  plates.  In  many  re- 
spects their  manufacture  resembles  that  of  "  Gelatine 
Veneers." 

Gelatine  foils  are  used  for  printing  sacred  images,  visiting 
cards,  labels,  in  the  manufacture  of  fancy  articles,  artificial 
flowers,  etc. 

For  the  manufacture  of  artificial  flowers  very  soft  and 
flexible  sheets  are  made  by  adding  J  part  of  glycerine  to 
1  part  of  gelatine  and  mixing  intimately  in  dissolving 
the  gelatine. 

Such  gelatine  sheets  brushed  over  in  addition  with  Peru- 
vian balsam  can  also  be  advantageously  used  for  tying  up 
wounds  instead  of  gutta-percha  cloth  which  tears  easily  and 
rots  soon.  They  form  an  air-tight  bandage  which  clings 
closely  to  the  parts  of  the  body,  and  beside  the  glycerine 
contained  in  them  exerts  a  beneficial  cooling  effect  and  acts 
as  an  antiseptic. 

Gelatine  Veneers. 

Franchi,  as  far  back  as  1814,  prepared  artificial  ivory  by 
mixing  gelatine  solution  with  earthy  substances.  This 
idea  has  been  again  taken  up  in  modern  times  for  the 
manufacture  of  veneers  imitating  not  only  ivory,  but  also 
avanturin,  lapis  lazuli,  malachite,  mother-of-pearl,  and 
tortoise  shell.  These  imitations  are  much  liked  by  manu- 
facturers of  fancy  articles,  workers  in  leather,  cabinet- 
makers, etc.  They  are  prepared  as  follows  : — 

The  process  may  be  divided  into  five  principal  opera- 
tions:  1.  Preparation  of  the  glass  and  marble  plates;  2. 
Preparation  of  the  glue  solutions ;  3.  Pouring  the  colored 
solutions  upon  the  plates  ;  4.  Transferring  the  layer  of  glue 
to  the  layer  of  gelatine  ;  and  5.  Drying  the  veneers  and  de- 
taching them  from  the  plates. 


MANUFACTURE    OF    GELATINE.  187 

1.  Preparation  of  the  plates.     Both  marble  and  glass  plates 
are  used  for  imitations  of  marble,  but  glass  plates  only  for 
imitations   of  mother-of-pearl.     The  glass  plates  must  be 
ground,  but  need  not  exceed  0.11  to  0.15  in.  in  thickness, 
and  only  require  careful  washing  and  drying  for  imitations 
of  mother-of-pearl.     For  imitations  of  marble  they  should 
be   rubbed  with   an   oiled  linen  rag.     Other  glass  plates, 
after   being    washed    and    polished  with    elutriated    rouge 
and  water,  are  wiped  with  a  soft  rag  to  remove  any  particle 
of  the  polishing  powder.     The   polished    surface   is   then 
gently  rubbed   with  a  rag  dipped  in  pure  Spanish  chalk, 
and  the  excess  of  chalk  carefully  dusted  off. 

2.  Preparation  of  the  glue  solutions.     For  one  dozen  plates, 
each  10}  square  feet,  soak  2  Ibs.  of  good,  colorless  glue  in 
water  for  24  hours,  pour  off  the  water  and  melt  the  glue  in 
a  water-bath  and  stir  in  3J  ozs.  of  glycerine.     For  imitating 
marbles  of  two  colors,  compound  20  to  24  fluidourrces  of 
this  glue  solution  with  the  quantities  of  thoroughly  ground 
mineral  colors  given  below  ;  the  rest  of  the  glue  solution  is 
mixed  with  6.34  ozs.  of  zinc  white  ground  very  fine.     For 
imitating  marble  of  three  colors  mix  14  fluidounces  of  the 
glue    solution   with    one   of   the  coloring  matters  and   14 
fluidounces  with  the  other  coloring  matter,  and  the  remain- 
der  with    zinc   white.     For   imitating   marble   with    four 
colors,  take  10  fluidounces  of  the  glue  solution  to  each  of 
the  three  coloring  matters,  and  mix  the  rest  with  4J  ozs.  of 
zinc  white. 

The  proportions  by  weight  of  the  mixtures  for  10  differ- 
ent varieties  of  imitations  of  marble  and  enamel  are  as  fol- 
lows : — 

a.  Mix  20  fluidounces  of  the  glue  solution  with  If  ozs.  of 
rouge  and  2J  ozs.  of  zinc  white,  and  the  rest  of  the  glue 
solution  with  6J  ozs.  of  zinc  white. 

b.  Mix  20  fluidounces  of  the  glue  solution  with  If  ozs. 
of  rouge,  and  the  rest  of  the  glue  solution  with  5J  ozs.  of 
zinc  white. 


188  GLUE,    GELATINE,    CEMENTS,    PASTES. 

c.  Mix  14  fluidounces  of  the  glue  solution  with  1J  ozs. 
of  zinc  white   and  1  oz.  of  rouge,  14  fluidounces  of  the 
glue  solution  with  1  oz.  of  yellow  ochre,  and  the  rest  with 
5J  ozs.  of  zinc  white. 

d.  Mix  14  fluidounces  of  the  glue  solution  with  1  oz.  of 
rouge,  14    fluidounces  of  the  glue  solution    with  f  oz.   of 
sepia,  and  the  rest  with  5J  ozs.  of  zinc  white. 

e.  Compound  20  J  fluidoiinces  of  the  glue  solution  with 
1  oz.  of  quite  concentrated  and  filtered  solution  of  aniline 
black,  and  the  rest  with  6J  ozs.  of  zinc  white. 

/.  Mix  10  ozs.  of  the  glue  solution  with  0.8  oz.  of  rouge, 
10  fluidounces  of  the  glue  solution  with  0.8  oz.  of  yellow 
ochre,  10  fluidounces  of  the  glue  solution  with  0.8  oz.  of 
sepia,  and  the  rest  with  4J  ozs.  of  zinc  white. 

g.  Mix  20.3  fluidounces  of  the  glue  solution  with  1.41 
ozs.  of  lampblack.  For  gray  add  sufficient  zinc  white  to 
produce  the  desired  shade.  The  rest  of  the  glue  solution  is 
mixed  with  6  J  ozs.  of  zinc  white. 

h.  Mix  10  fluidounces  of  the  glue  solution  with  0.8  oz.  of 
umber,  10  fluidounces  of  the  glue  solution  with  0.8  oz.  of 
bole,  10  fluidounces  of  the  glue  solution  with  0.8  oz.  of 
ochre,  and  the  rest  with  4J  ozs.  of  zinc  white. 

i.  For  enamels  mix  20.3  fluidounces  of  the  glue  solution 
with  1  oz.  of  ultramarine,  and  the  rest  with  6J  ozs.  of  zinc 
white. 

k.  Mix  20.3  fluidounces  of  the  glue  solution  with  1.41  ozs. 
of  chrome  green,  and  the  rest  with  6J  ozs.  of  zinc  white. 

For  imitating  mother-of-pearl  veneers,  0.42  oz.  of  silver 
bronze,  which  need  not  be  genuine,  is  ground  with  a  little 
glue  solution  or  water  and  intimately  mixed  with  the  above 
solution  of  glue.  The  bronze  powder  must  not  be  in  a  dry 
state  when  stirred  into  the  glue,  as  lumps  would  be  formed 
and  the  veneers  become  spotted.  In  place  of  bronze,  essence 
of  fish  scales,  which  is  of  course  far  more  costly,  can  be 
used.*  The  glue  solution  thus  prepared  is  then  com- 

*  This  preparation  is  also  known  by  the  name  Essence  d'  Orient.     The  mate- 


MANUFACTURE    OF    GELATINE.  189 

pounded  with  different  aniline  colors  according  to  the  tint 
desired. 

a.  For  yellowish  veneers  no  coloring  matter  is  required, 
or  the  desired  shade  is  obtained  by  an  addition  of  some 
solution  of  picric  acid. 

b.  For  colorless  veneers  or  those  of  slightly  reddish  tints 
a  smaller  or  greater  number  of  drops  of  a  concentrated  solu- 
tion of  fuchsine  are  added  in  order  to  counteract  the  yel- 
lowish color  of  the  glue  solution.     For  these  imitations  of 
mother-of-pearl   veneers,   concentrated  solution   of  gelatine 
compound  with  15  per  cent,  of  glycerine  can  be  employed, 
especially  when  essence  of  fish  scales  is  used. 

c.  For  blue,  the  glue  solution  is  compounded  with  bleu  de 
Lyons,  care  being  had  not  to  use  too  much,  as  otherwise  the 
imitation  becomes  indistinct.     The  proper  degree  of  color- 
ing is  tested  by  allowing  a  few  drops  of  the  colored  glue 
solution  to  fall  upon  a  glass  plate. 

d.  For  red,  solution  of  fuchsine  or  carmine  is  used,  the 
latter  being  obtained   by   dissolving  commercial   carmine 
powder  in  alcohol. 

e.  Orange  colors  are  produced   by  an  addition  of  solution 
of  chrysaniline  generally  sold  under  the  name  of  Victoria 
orange,  and  violet  by  adding  aniline  violet.     For  these,  as 
well  as  for  the  solution  colored  with  fuchsine,  the  plates 
must  not  be  rubbed  with  oil,  as  even  the  smallest  trace  of 
the  latter  discolors  these  colors  in  drying,  or  at  least  the 
veneers  will  show  spots  without  color. 

3.  Pouring  the  colored  solutions  of  glue  upon  the  plates. 
For  imitations  of  marble  and  enamel,  the  glass  plates,  after 
rubbing  with  oil,  are  placed,  rubbed  surface  up,  in  a  per- 

rial  for  its  production  is  furnished  by  a  small  white  fish  very  common  in  the 
rivers  of  continental  Europe.  It  accompanies  the  scales  of  this  fish,  and  is 
detached  when  the  scales  are  triturated  for  a  considerable  time  and  thrown  into 
a  vessel  of  water.  To  collect  the  essence  the  water  is  poured  off  upon  a  fine 
hair  sieve,  which  retains  the  scales  and  allows  the  water  and  the  product 
sought  to  pass  through.  The  latter  sinks  to  the  bottom,  and  is  obtained  pure 
by  decanting  the  water.  A  little  ammonia  is  added  to  prevent  decomposition. 


190  GLUE,    GELATINE,    CEMENTS,    PASTES. 

fectly  level  position.  The  proper  portion  of  the  white 
ground-mass,  after  becoming  somewhat  thickish,  is  then 
poured  upon  the  plates,  and  the  gaps  left  free  in  pouring 
filled  in  and  smoothed  with  a  knife-shaped  tool  of  horn  or 
bone.  Upon  this  white  ground  the  respective  colored  glue 
solutions  are  then  poured  in  a  zigzag  form,  and  in  conform- 
ity with  the  desired  design,  drawn  through  the  ground- 
mass  with  a  glass  rod.  If  several  differently  colored  glue 
solutions  are  to  be  applied,  as  given,  for  instance,  under  2/, 
they  should  be  poured  in  quick  succession,  so  that  the  suc- 
ceeding color  runs  into  the  preceding,  and  a  white  strip 
or  spot  remains  between  each  color.  The  whole  is  then  in- 
termingled by  the  glass  rod,  according  to  the  design.  If 
the  latter  is  to  have  sharply  defined  lines  and  spots,  the  re- 
spective colored  solution  of  glue  is  used  somewhat  thicker, 
but  if,  on  the  other  hand,  the  design  is  to  be  somewhat 
blended,  the  glue  solutions  are  used  somewhat  warmer,  and 
consequently  more  thinly  fluid.  After  solidification  of  the 
glue  solutions  the  plates  are  placed  in  a  cool  room  for  two 
or  three  hours. 

Imitations  of  malachite  are  prepared  in  a  similar  manner. 
Four  glue  solutions  of  different  shades  of  green  from  the 
darkest  to  the  lightest  tint  are  prepared  and  poured  upon  a 
slightly  greenish  ground,  so  as  to  imitate  the  characteristic 
curves  and  veins  of  malachite,  which  are  then  further 
traced  with  a  comb  with  teeth  standing  at  unequal  distances 
from  each  other. 

The  glass  plates  set  aside  to  be  used  for  imitation  of 
mother-of-pearl  are  now  taken  in  hand.  The  solutions  of 
glue  are  kept  warm  over  a  water  bath  and  thoroughly 
stirred  every  time  before  pouring  them  upon  the  plates. 
The  formation  of  a  film  on  the  surface  of  the  glue  solution 
must  be  strictly  avoided. 

For  pouring  out  the  solutions  it  is  best  to  use  a  porcelain 
vessel  provided  with  a  spout  and  handle,  and  having  a 
capacity  of  about  6f  fluid-ounces.  The  portion  of  glue 


MANUFACTURE    OF    GELATINE.  191 

solution  required  for  each  plate  (1}  flu.  oz.)  is  then  meas- 
ured into  one  of  the  porcelain  vessels,  and,  after  standing  a 
short  time,  poured  upon  the  plate  and  uniformly  distributed. 
The  production  of  a  mother-of-pearl  design  requires  some 
skill  and  practice.  A  comb  with  teeth  set  J  inch  apart  is 
used.  It  is  held  in  a  somewhat  oblique  position,  the  teeth 
are  gently  pressed  upon  the  glass  plate,  and,  with  frequent 
turnings  of  the  comb  at  a  right  angle,  cycloidal  motions 
executed.  The  operation  is  carried  on  from  the  front  to  the 
back  edge  of  the  glass  plate,  and  when  the  glue  begins  to 
thicken  on  the  edges,  continued  at  the  softer  places  until 
the  desired  design  is  produced,  care  being  had  not  to  touch 
places  which  have  already  acquired  a  certain  degree  of 
solidity,  as  this  would  mar  'the  pattern.  After  treating  all 
the  plates  in  this  manner,  they  are  set  aside  in  a  cool  room 
for  two  or  three  hours. 

4.  Transferring  the  layer  of  glue  to  a  layer  of  gelatine.  For 
each  dozen  of  veneers  soak  2|  ozs.  of  gelatine,  and  then 
melt  them  in  a  water-bath,  and  after  adding  glycerine 
equal  to  10  per  cent,  of  the  dry  gelatine,  let  the  mixture 
settle. 

The  glass  plates  treated  with  rouge  and  Spanish  chalk  are 
now  placed  in  a  perfectly  level  position,  and  after  pouring 
5J  fl.  ozs.  of  gelatine  solution  upon  each  of  them,  the  gaps 
left  in  pouring  are  filled  in  and  smoothed  with  the  glass 
rod.  The  front  edge  of  a  plate  covered  with  a  colored  layer 
of  glue  is  now,  glue  side  down,  placed  upon  the  front  edge 
of  a  gelatine  plate,  while  the  back  edge  of  the  former  is 
gradually  lowered  until  the  glue  plate  lies  firmly  upon  the 
gelatine  plate. 

It  may  here  be  remarked  that  the  gelatine  solution  must 
only  be  allowed  to  cool  off  sufficiently  to  prevent  the  melt- 
ing of  the  glue  plate  on  touching  it.  If  it  is  cooler  the 
veneers  will  have  blisters.  It  must  further  be  looked  to 
that,  before  placing  the  first  plate  upon  the  gelatine  plate, 
no  gelatine  escapes,  and  that  any  excess  only  runs  off  after 


192  GLUE,    GELATINE,    CEMENTS,    PASTES. 

the  back  edge  of  the  glue  plate  touches  that  of  the  gelatine 
plate. 

The  plates  are  now  allowed  to  rest  quietly  until  the  gela- 
tine is  congealed,  when  they  are  removed  to  a  cool  place 
where  they  remain  five  or  six  hours. 

Imitations  of  mother-of-pearl  are  treated  in  the  same 
manner  with  the  exception  that  the  gelatine  solution  is 
colored  with  the  same  coloring  matter  as  the  glue  solution. 
For  colorless  or  yellowish  veneers  the  gelatine  solution  is 
not  colored. 

After  six  hours  the  first  glass  plate  is  detached  from  the 
layer  of  glue  by  loosening  the  latter  around  the  edges  with 
a  knife  blade,  and  the  plate  gradually  lifted  off  commencing 
at  one  corner.  With  some  care  and  skill,  this  operation  is 
readily  accomplished  without  detaching  the  gelatine  mass. 

5.  Drying  and  detaching  the  veneers.  The  veneers  with 
the  gelatine  layer  still  adhering  to  the  glass  plate  are  now 
dried.  This  is  done  in  a  heated  room  in  which  the  veneers 
are  arranged  upon  frames  so  that  they  stand  almost  per- 
pendicular. The  hot  air  for  heating  the  room  enters  near 
the  ceiling  while  the  moist  air  is  drawn  away  near  the 
floor.  The  temperature  of  the  lower  zone  where  the  fresh 
plates  are  placed  should  not  exceed  68°  F.  The  plates  are 
moved  up  higher  every  day  until,  on  the  third  or  fourth 
day,  they  have  become  entirely  dry.  Before  removing  the 
veneers  from  the  drying-room  they  should  be  tested  in 
regard  to  their  dry  ness.  They  are  sufficiently  dry,  when, 
on  pressing  the  finger  nail  upon  the  glue,  no  impression  is 
made. 

After  removal  from  the  drying-room  the  plates  are  al- 
lowed to  cool  off  for  at  least  two  hours  before  detaching  the 
veneers.  The  operation  begins  by  detaching  the  gelatine 
layer  on  the  edges  with  a  very  thin  knife  blade.  The 
operator  then  takes  hold  of  one  corner  of  the  veneer  and 
draws  it  gradually  and  carefully  from  the  glass  plate. 
After  trimming  the  edges  the  veneers  are  ready  for  use. 


MANUFACTURE    OF    GELATINE.  193 

If  the  veneers  are  required  to  resist  the  action  of  water, 
mix  with  the  solution  of  gelatine  compounded  with  glycer- 
ine J  fl.  oz.  of  a  solution  of  5  parts  of  chrome-alum  in  100 
of  water  to  every  plate,  and  immerse  the  veneers  for  a  short 
time  after  they  have  been  detached  from  the  first  plate,  in 
a  similar  solution  of  chrome-alum. 

Veneers  prepared  by  these  methods  can  be  used  for  var- 
ious purposes  in  architecture  and  in  the  manufacture  of 
furniture.  Tennessee  and  other  marbles  have  been  so 
closely  imitated,  that  when  used  for  table  plates,  etc.,  the 
fact  of  their  being  imitations  could  only  be  detected  by  the 
closest  scrutiny.  The  veneers  are  also  much  used  for  fancy 
and  inlaid  work,  for  coating  columns,  etc.  To  prevent 
their  blistering  and  coming  off,  it  is  recommended  to  add 
one-quarter  of  its  weight  of  glycerine  to  the  glue  with  which 
they  are  to  be  attached  to  the  articles. 

Formo-  Gelatine. 

This  product  is  used  as  a  dressing  in  surgery,  and,  ac- 
cording to  Samuel  Rideal,  is  obtained  as  follows :  Gelatine 
in  aqueous  solution  is  precipitated  by  formaldehyde  H.COH, 
or  CH20,  as  a  substance  which  on  drying  is  a  white  powder, 
neutral,  inodorous,  and  insoluble  in  water  and  dilute  chem- 
ical agents.  In  commerce  formaldehyde  is  met  with  in 
aqueous  solution  as  "  formalin  "  containing  40  per  cent,  of 
formaldehyde.  If  1  Cc.  of  formalin  be  added  to  200  Cc.  of 
a  5  per  cent,  gelatine  solution,  the  latter  is  changed  into  a 
gelatinous  mass,  not  melted  by  heat  nor  reduced  by  water. 
If  a  smaller  quantity  of  the  formalin  is  added  (1  in  1000 ; 
the  jelly  is  said  to  be  meltable,  but  with  a  higher  tenacity) 
when  dried  it  becomes  insoluble  in  warm  water.  Formalin 
in  less  proportion,  though  it  does  not  prevent  the  dried 
gelatine  from  dissolving  in  warm  water,  is  said  to  improve 
the  "  body  "  of  the  jelly  and  its  keeping  qualities,  and  also 
the  tenacity  of  the  glue.  The  results  of  investigation  show 
that  with  up  to  1  per  cent,  of  formalin  the  solidity  of  the 
13 


194  GLUE,    GELATINE,    CEMENTS,    PASTES. 

jelly  increases  ;  above  that  it  declines.  Up  to  0.02  per  cent. 
(1  in  5,000)  it  redissolves  in  water  after  drying.  Even  with 
this  small  proportion  the  firmness  of  the  jelly  is  sensibly 
increased.  The  English  patent,  4,696,  1894,  claims  the  ad- 
dition of  formalin  during  the  manufacture  of  size  and  glue 
in  such  proportion  that  the  product  shall  liquefy  in  warm 
water. 

In  examining  commercial  sheet  gelatines  for  printers' 
and  photographic  use,  they  were  often  found  to  contain 
small  quantities  of  formalin.  It  seems  to  improve  the  qual- 
ity, a  very  small  percentage  increasing  the  tenacity,  flexi- 
bility and  keeping  qualities,  while  not  affecting  the  trans- 
parency or  rendering  the  material  acid.  When  applied  to 
articles  that  may  be  used  as  food,  a  strength  of  1  in  50,000 
in  the  final  prepared  product  is  not  injurious  to  health,  but 
should  not  be  exceeded.  (Rideal  and  Foulerton,  Public 
Health,  May,  1899,  p.  568.) 

Zimmermann  applies  dilute  formaldehyde  mixed  with 
glycerine,  vaseline,  oil  or  yolks  of  eggs,  with  or  without 
flour,  to  the  surface  of  photographic  films  which  are  claimed 
to  be  thereby  rendered  more  pliable  and  not  so  hard  as 
when  the  formalin  is  applied  by  itself. 

It  will  be  seen  that  formaldehyde  in  more  than  traces 
renders  gelatine  insoluble  ;  the  product,  moreover,  is  almost 
unaffected  by  water,  is  more  or  less  hard  and  elastic  and, 
owing  to  the  antiseptic  properties  of  the  formaldehyde  is 
nearly  imperishable. 

Use  of  Gelatine  in  Bacteriology. 

Gelatine  fit  for  this  purpose  must  be  clear  and  bright, 
fairly  neutral  and  of  high  gelatinizing  power.  For  bacter- 
iological purposes  a  10  to  20  per  cent,  solution  of  gelatine 
in  sheets  or  strips  is  made  with  meat  broth,  and  this  nutrient 
jelly,  which  is  obtained  by  clarification  with  albumen  per- 
fectly clear  and  bright,  forms  a  most  useful  medium  for  the 
cultivation  of  micro-organisms. 


MANUFACTURE    OF    GELATINE.  195 

Artificial  Silk  from  Gelatine. 

For  the  production  of  textile  threads,  Millar  utilizes  the 
property  of  gelatine  solution  mixed  with  potassium  dichro- 
mate,  becoming  insoluble  on  exposure  to  light.  For  this 
purpose  a  clear  solution  of  gelatine  is  mixed  with  solution 
of-  potassium  dichromate  in  the  proportion  of  100  parts  of 
gelatine  to  2  or  2J  parts  of  potassium  dichromate.  The 
fluid  should  be  of  such  a  consistency  as  to  allow  of  its  being 
drawn  out  into  fine  threads  which  on  exposure  to  light 
become  insoluble.  Silk  woven  from  such  threads  is  equal 
in  appearance  to  the  genuine  article  but  of  course  is  not  so 
strong.  It  is  affected  by  moisture,  becoming  limp,  but  re- 
gains its  normal  strength  when  dry.* 

*  For  further  information  on  this  interesting  subject,  the  reader  is  referred 
to  u  Cellulose  and  Cellulose  Products."  By  Dr.  Joseph  Bersch.  Henry 
Carey  Baird  &  Co.,  Philadelphia,  1904. 


CHAPTER  X. 

ISINGLASS  AND  ITS  SUBSTITUTES. 

ISINGLASS  is  obtained  from  the  air-bladder  or  sound,  as  it 
is  sometimes  termed,  of  different  kinds  of  fishes,  especially 
of  the  sturgeon,  species  Acipenser.  It  is  used  for  culinary 
purposes,  fining  beer  and  other  liquids,  for  making  court- 
plaster  and  stiffening  silk,  though  a  good  quality  of  gelatine 
is  practically  equal  to  it  for  these  purposes.  A  good  quality 
of  isinglass  should  be  pure  white,  semi-transparent,  dry  and 
horny  in  texture,  and  free  from  odor.  It  should  dissolve 
in  water  of  95°  to  122°  F.,  without  leaving  any  residue, 
and,  on  cooling,  should  yield  an  almost  colorless  jelly. 
From  gelatine  imitations  it  is  distinguished  by  soaking  it 
in  warm  water  and  examining  under  the  microscope,  when 
true  isinglass  will  show  a  net-work  of  long,  curling  fibres, 
while  gelatine  will  be  simply  hyaline.  Isinglass  is  often 
imitated  with  the  intestinal  membranes  of  the  calf  and  of 
the  sheep.  This  spurious  article  may  be  readily  recognized 
because  it  does  not  exhibit,  like  isinglass,  a  sort  of  shining 
appearance  when  held  before  the  eye  and  daylight,  and 
because,  although  inodorous,  it  has  a  saltish  flavor.  If  it 
be  torn  asunder  it  will  be  observed  that  it  may  be  rent  in 
all  directions,  while  true  isinglass  cannot  be  divided  other- 
wise than  in  the  direction  of  its  fibres.  If  a  piece  of  arti- 
ficial isinglass  be  macerated  in  water  it  swells,  but  instead 
of  retaining  its  shape  as  is  the  case  with  the  genuine 
article,  it  becomes  divided  into  several  pieces,  forming  a 
sort  of  curdy  precipitate  ;  and  if  treated  with  boiling  water, 
about  one-third  of  its  weight  is  left  in  an  insoluble  state, 
and  the  liquor  does  not  form  a  good  jelly.  Isinglass  is 
frequently  adulterated  with  gelatine,  which  is  inserted 

(196) 


ISINGLASS    AND    ITS    SUBSTITUTES.  197 

between  the  leaves  and  rolled  up  with  it.  The  best  indica- 
tion of  this  adulteration  is  the  amount  of  ash  ;  isinglass 
yields  only  0.9  per  cent.,  while  gelatine  yields  4  per  cent., 
and  adulterated  isinglass  1.5  per  cent,  or  more. 

1.  Russian  isinglass.  Russia  produces  the  best  and  most 
isinglass.  It  is  chiefly  obtained  from  several  varieties  of 
sturgeon,  species  Acipenser,  which  inhabit  the  Caspian  and 
Black  Seas,  and  their  tributary  rivers.  The  Acipenser 
Gueldenstaedtii,  Br.  yields  the  finest,  best  and  whitest  isin- 
glass. It  is  known  by  the  name  of  Patriarch,  and  consists 
of  small  horseshoe-shaped  pieces  rolled  tightly  together. 
It  is  quite  scarce  and  expensive.  When  the  bladder  is 
merely  dried  in  sheets,  it  constitutes  leaf  isinglass.  When 
several  bladders  are  put  together  and  folded  before  they  are 
completely  dry,  they  form  book  isinglass.  Each  bladder 
may  also  be  rolled  up  and  folded  around  a  few  pegs  in  the 
form  of  a  horseshoe,  heart,  or  lyre,  in  which  shape  it  is 
dried.  The  latter  is  the  staple  isinglass,  which,  according 
to  its  dimensions,  is  again  divided  into  long  and  short  staple. 

Long  staple  isinglass  of  fine  quality  is  produced  in  the 
Oural.  It  is  imported  in  loose  leaves,  and  at  times  it  is 
twisted  like  ropes,  this  kind  being  preferred,  as  it  is  inferior 
in  quality  only  to  Patriarch. 

Siberian  purse  isinglass  is  of  moderately  good  quality  and 
is  in  general  demand.  A  small  kind  of  strings  in  a  neck- 
lace form  is  sometimes  imported. 

A  very  good  sort  of  Russian  isinglass  comes  into  com- 
merce in  leaves  and  books,  and  is  known  by  the  name  of 
Samovey  leaf.  It  is  obtained,  according  to  the  statements  of 
Russian  merchants,  from  the  common  sheath-fish  (Siluris 
Glanis).  The  pieces  are  as  large  as  a  hand,  of  the  thick- 
ness of  pasteboard,  very  solid,  not  very  flexible  and  of  a 
white-yellowish  color.  It  is  inferior  in  quality  to  Astrakhan 
isinglass,  which  is  one  of  the  best  kinds. 

In  Russia  the  isinglass  is  generally  prepared  by  boys 
under  the  supervision  of  elder  experts.  The  swimming 


198  GLUE,    GELATINE,    CEMENTS,    PASTES. 

bladder  is  first  placed  in  water  and  left  there  for  some  days 
with  frequent  changes  of  the  water  and  removal  of  all  fatty 
and  bloody  particles.  The  warmer  the  water  the  more 
rapidly  the  operation  is  completed.  The  bladders  are 
finally  removed  and  cut  longitudinally  into  sheets  which 
are  exposed  to  the  sun  and  air,  being  laid  out  to  dry,  with 
the  outer  face  turned  down,  upon  boards  of  linden  or  bass 
wood.  The  inner  face  is  pure  isinglass,  which,  when  well 
dried,  can  with  care  be  removed  from  the  external  lamella. 
The  finer  sheets  thus  obtained  are  placed  between  cloths 
to  protect  them  from  the  flies,  and  are  then  subjected  to  a 
heavy  pressure  so  as  to  flatten  them  out  and  render  them 
uniform.  After  this  they  are  assorted  and  tied  up  in  pack- 
ages. The  packages  composed  of  the  isinglass  of  the  large 
sturgeon  usually  contain  from  ten  to  fifteen  sheets  and 
weigh  a  pound  and  a  quarter ;  those  of  the  other  contain 
twenty-five  sheets  weighing  a  pound.  Eighty  of  these 
packages  are  usually  sewed  up  in  a  cloth  bag,  or  sometimes 
inclosed  in  sheet  lead. 

The  outer  lamellse  of  the  air-bladder,  after  the  isinglass 
has  been  removed,  also  contain  a  considerable  quantity  of 
glue  which,  when  softened  in  water,  is  scraped  off  with  a 
knife  and  moulded  into  little  tablets  of  about  the  size  of  a 
silver  dollar,  and  then  dried. 

2.  North  American  or  New  York  Isinglass.  It  is  in  thin 
strips  several  feet  long  but  J  to  1J  inch  wide.  It  is  less 
soluble  than  Russian  isinglass,  and  yields  frequently  a  dark- 
colored  solution.  It  is  prepared,  according  to  Dr.  J.  V.  C. 
Smith's  statements,  from  the  air-bladder  of  the  common 
hake  (Gadus  merluccius),  which  is  macerated  in  water  for  a 
short  time,  cut  open  and  subjected  to  pressure  between  iron 
rollers,  by  which  it  is  elongated  to  the  extent  of  half  a  yard 
or  more.  It  is  then  carefully  dried,  packed  and  sent  to 
market.  The  air-bladder  of  the  common  cod  (Gadus 
morrhua)  is  prepared  in  a  similar  manner,  but  yields  a 
poorer  kind  of  isinglass. 


ISINGLASS    AND    ITS    SUBSTITUTES.  199 

3.  East  India  Isinglass.     It  would  seem  that  for  a  long 
time  this  has  been  exported  from  Calcutta  to  China,  but  has 
only  lately  attracted  the  attention  of  European  dealers.     It 
is  prepared  from  the  air-bladder  of  the  Polynemus  plebejus, 
and  comes  into  commerce  either  in  the  form  of  leaves  or 
.purses  which  seem  to  consist  of  the  unopened   air-bladder. 
East  Indian  isinglass  has  a  disagreeable  fish  odor,  due  very 
likely  to  careless  preparation,  which  makes  its  use  impossi- 
ble for  many  purposes,  and,  of  course,  depreciates  its  com- 
mercial value.     The    oval-oblong   purses   are   about   nine 
inches  long,  three  and  a  half  inches  wide,  weigh  about  7 
ozs.  and  have  a  dark -yellow  color.     East  India  leaf  isin- 
glass, i.   e.,  the  opened  and   dried  air-bladder,  consists  of 
yellowish-colored  leaves  eight  to  nine  inches  long,  six  to 
seven  inches  wide,  and  about  three-tenths  of  an  inch  thick. 
The  leaves  are  sometimes  rolled  out  into  long  ribbons  about 
one-tenth  of  an  inch  thick,  the  surface  of  which  is  covered 
in  places  with  a  thin  film  of  lime. 

What  is  known  as  picked  East  India  isinglass  is  brought 
into  commerce  in  small  shreds  about  two  to  three  inches 
long,  and  tapering  at  the  extremities. 

A  variety  of  isinglass  very  white  and  pure  and  scarcely 
inferior  to  Samovey  leaf  is  brought  from  Manila.  The 
fish  which  yields  it  is  caught  on  the  coast  of  the  Philippine 
Islands,  especially  at  Luzon. 

4.  Hudson  Bay  Isinglass.     It  is  brought  into  commerce 
in  the  purse  form.     Some  specimens  measure  twelve  inches 
in   length   and   three  and  a  half  inches  in  diameter,  and 
weigh  one  and  a  half  ounces.     It  is  of  light-yellow  color, 
nearly  transparent,  without  odor  or  taste.     The  inner  lin- 
ing of  the  sac,  which  can  be  readily  stripped  off,  is  insoluble 
in  water,  while  the  remaining  portion  dissolves  to  a  slightly 
colored  jelly.    We  have  been  unable  to  ascertain  from  what 
species  of  fish  this  isinglass  is  procured. 

5.  Brazilian  Isinglass.     This  is  imported  from  Para  and 
Maranham,  and  is  also  called  Cayenne  isinglass.     For  a  long 


200  GLUE,    GELATINE,    CEMENTS,    PASTES. 

time  there  existed  a  doubt  from  what  species  of  fish  this 
isinglass  was  procured,  but  it  is  now  settled  that  it  is  pre- 
pared from  the  air-bladder  of  Silurus  Parkerii,  a  fish  which 
is  frequently  found  in  the  muddy  waters  of  the  rivers  in 
the  province  of  Grao  Para,  where  these  waters  mingle  with 
the  sea. 

Brazilian  isinglass  comes  in  the  form  of  pipe,  lump  and 
honeycomb.  On  account  of  its  dark  color  it  is  not  in  much 
demand  for  ordinary  use,  but  is  frequently  employed  in 
England  for  clarifying  glue.  When  digested  in  water  it 
leaves  much  insoluble  substance  behind,  being  in  this 
respect  also  inferior  to  Russian  isinglass. 

6.  German  Isinglass.  Under  this  name  we  may  mention 
the  mucous  membrane  of  the  sturgeon  (Acipenser  sturio), 
prepared  in  Hamburg.  When  boiled  with  water  it  leaves 
16  per  cent,  of  insoluble  substance. 

It  is  said  that  an  excellent  isinglass  can  be  made  from 
the  scales  of  shad  and  herring,  which  are  first  freed  from 
their  silvery  coating.  This  may  furnish  a  useful  hint  to 
persons  who  are  near  some  of  the  great  fishery  establish- 
ments of  the  country,  at  Gloucester,  N.  J.,  and  Alexandria, 
Va.,  for  instance,  where  thousands  of  shad  are  scaled  and 
salted  every  year. 

To  give  inferior  qualities  of  isinglass  a  better  appearance 
and  make  them  more  salable,  they  are  frequently  bleached 
with  sulphurous  acid. 

Ichthyocolle  Franqaise.  Under  this  name,  Rohan  has 
introduced  a  substitute  for  isinglass.  The  material  used 
for  its  manufacture  is  blood  fibrin,  which,  after  washing  in 
running  water,  is  thoroughly  kneaded  and,  after  draining, 
digested  at  59°  F.  with  dilute  sulphuric  acid  of  8°  to  10° 
Be.  for  eight  days,  after  which  the  mass  is  freed  from  acid 
by  washing  in  running  water. 

The  fibrin  freed  from  acid  becomes  transparent  and  gela- 
tinous by  treating  with  weak  soda  lye  of  3°  to  4°  Be.  at 
59°  F.,  whereby  it  swells  up  and  increases  hourly  in  vol- 


ISINGLASS    AND    ITS    SUBSTITUTES.  201 

urne.  After  twenty-four  hours  it  is  taken  from  the  soda 
lye,  and  after  removing  the  free  soda  by  washing,  heated  to 
212°  F.  in  a  water-bath.  The  fibrin  dissolves  and  becomes 
so  thinly  fluid  that  it  can  be  filtered.  75  to  80  per  cent,  of 
the  water  is  then  evaporated,  and  the  fibrin  thus  prepared 
can  be  used  as  a  substitute  for  isinglass  for  fining  purposes. 
Ichthyocolla  swells  more  quickly  in  cold  water  than  isin- 
glass ;  15  to  20  per  cent,  divided  in  water  forms  a  thickly 
fluid  substance,  which  on  heating  dissolves  to  a  perfectly 
clear  fluid.  For  fining  beer  with  ichthyocolla  add  2  to  10 
per  cent,  of  pure  tannin,  which  does  not  injure  its  power  of 
dissolving. 

Isinglassine.  Under  this  name  is  known  an  isinglass 
substitute  prepared  from  the  gelatinous  material  from 
calves'  feet  and  other  sources.  The  material  is  reduced  by 
machinery  to  a  pliable  homogeneous  mass,  rolled  out  into 
sheets,  dried,  pressed  and  shredded. 

Chinese  isinglass  is  identical  with  the  Japanese  Agar-Agar, 
and  is  obtained  by  cleansing  and  boiling  certain  species  of 
algae  found  in  Chinese  and  Japanese  waters.  This  isin- 
glass, or  gelatine,  possesses  the  following  properties  : 

Placed  in  cold  water  it  softens  without  dissolving  like 
gelatine,  and  forms  a  structureless  tubular  mass  which  is 
not  sticky.  By  boiling,  it  dissolves  more  readily  than  isin- 
glass, but  with  greater  difficulty  than  gelatine.  A  1  to  2 
per  cent,  solution  .is  easily  filtered  through  paper  or  linen, 
and  when  cold  forms  a  solid  jelly  clear  as  water  and  with- 
out taste  or  odor.  Jelly  prepared  with  one-half  per  cent,  of 
Chinese  gelatine  is  more  solid  than  one  prepared  with  4  per 
cent,  of  French  white  gelatine,  retains  its  consistency  longer, 
and  will  stand  a  temperature  of  86°  to  122°  F.  before  be- 
coming liquid.  Used  for  jellies,  or  mixed  with  other  foods, 
it  does  not  impart  to  them  a  glue  taste  never  wanting  in 
bone  gelatine.  When  decomposed  by  long  standing,  it  does 
not  acquire  a  disagreeable  odor,  while  decomposed  isinglass 
or  gelatine  exhales  a  putrid  smell. 


202  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Agar-Agar  contains,  according  to  analyses :  Cellulose, 
starch,  gum,  dextrine,  vegetable  mucus,  vegetable  wax, 
resin,  chlorophyll,  albumen,  a  peculiar  acid,  and  several 
mineral  substances. 

Irish  moss  (Chondrus  crispus)  which  grows  on  rocks  of  the 
American  and  European  shores  of  the  Atlantic  Ocean, 
yields  a  jelly  which  has  been  employed  as  a  substitute  for 
isinglass,  as  a  size,  for  thickening  colors  in  calico  printing, 
and  in  stiffening  silk.  In  a  fresh  or  softened  state  the  plant 
is  cartilaginous,  of  a  brownish  or  purple,  or  frequently  yel- 
low or  green  color.  After  washing  in  water  and  drying  in 
the  sun  it  turns  whitish  or  yellowish,  and  becomes  some- 
what translucent  and  of  a  horny  appearance.  It  has  a 
slight  seaweed-like  odor  and  a  mucilaginous,  somewhat 
saline  taste.  One  part  of  it  boiled  with  20  parts  of  water 
gelatinizes  on  cooling. 

Fish  Glue. 

This  product,  which  is  prepared  in  many  localities  from 
fishes,  must  not  be  confounded  with  isinglass,  though  the 
purer  varieties  may  serve  as  substitutes  for  the  latter  or  for 
gelatine. 

Jennings  gives  the  following  process  for  the  preparation 
of  fish  glue.  The  fishes  are  treated  with  dilute  sulphuric 
acid  until  the  skin  can  be  detached.  The  acid  water  is 
then  drained  off  and  replaced  by  milk  of  lime  to  neutralize 
adhering  sulphuric  acid  as  well  as  to  saponify  the  fat.  The 
milk  of  lime  is  several  times  drained  off  and  renewed,  the 
mass  thoroughly  washed,  cut  up  in  a  hollander  and  treated 
cold  with  solution  of  sodium  hyposulphite,  common  salt 
and  alum.  After  a  few  days  the  liquor  is  drawn  off  and 
replaced  by  a  mixture  of  alum  solution,  dilute  sulphuric 
acid  and  nitric  acid  in  which  the  mass  is  allowed  to  remain 
for  a  few  days.  Fishes  with  dark  skins  are  treated  with  a 
mixture  of  hydrochloric  and  sulphuric  acids.  After  wash- 
ing, the  skin  is  removed  and  the  fibres  which  have  become 


ISINGLASS    AND    ITS    SUBSTITUTES.  203 

detached  from  the  bones  are  separated  by  digestion  in 
dilute  solution  of  mercuric  chloride  and  alura.  Adhering 
fatty  parts  are  removed  with  warm  milk  of  lime,  the  lime 
is  neutralized  with  hydrochloric  acid,  and  the  mass  boiled 
with  water  for  the  formation  of  glue.  The  resulting  glue- 
liquor  is  clarified  with  sulphurous  acid  and  alum,  and 
when  all  the  impurities  have  subsided,  compounded  with 
acid  sodium  carbonate  till  all  the  acid  is  neutralized.  The 
finished  solution  is  concentrated  so  that  it  gelatinizes  on 
cooling  and  can  be  cut  in  cakes  which  are  dried  in  the 
usual  manner. 

Fish  scales,  especially  those  of  carps,  are  treated  in  a 
similar  manner.  The  bone-earth  is  extracted  with  hydro- 
chloric acid,  the  extracted  material  thoroughly  washed,  and 
then  boiled  in  soft  water  till  it  can  be  readily  stirred.  The 
liquor  is  drawn  off  from  the  horny  sediment,  clarified  with 
alum,  evaporated,  and  after  all  the  impurities  have  sub- 
sided, poured  into  moulds  and  treated  like  ordinary  glue. 

Considerable  quantities  of  fish  glue  are  produced  on  the 
Norwegian  coast  from  waste  obtained  in  the  preparation  of 
codfish.  The  fish  when  caught  are  cut  open  and  the  air- 
bladders  removed,  which  are  dried  and  brought  into  com- 
merce as  isinglass.  The  head  is  then  cut  off  and  the  bones 
detached  in  one  piece.  The  flesh  is  dried  in  the  air,  and 
forms  the  codfish  of  commerce:  The  heads  and  bones  are 
first  treated  with  hydrochloric  acid  or  directly  boiled  under 
slight  pressure  in  water,  and  the  resulting  liquor  concen- 
trated so  that  it  will  gelatinize. 

A  substitute  for  isinglass,  also  for  gelatine  and  glue,  is 
prepared  by  C.  A.  Sahlstrohm,  of  Stockholm,  according  to 
his  patent,  from  fish  and  fish  waste  by  treatment  with 
bleaching  powder,  potassium  permanganate,  and  nitrous 
and  sulphurous  gases. 

For  this  purpose  the  fishes,  or  portions  of  fishes,  are  first 
well  washed  in  fresh  water  and  then  left  for  from  three  to 
four  hours  in  a  solution  of  bleaching  powder  (in  the  pro- 


204  GLUE,    GELATINE,    CEMENTS,    PASTES. 

portion  of  2  Ibs.  of  bleaching  powder  to  300  quarts  of  water). 
After  washing  they  are  treated  for  about  30  minutes  with  a 
solution  of  potassium  permanganate  (in  the  proportion  of 
If  ozs.  of  potassium  permanganate  to  250  or  300  quarts  of 
water),  and  then  exposed  to  the  action  of  the  nitrous  gas, 
produced  by  heating  10  to  15  ozs.  of  nitric  acid  for  every 
88  Ibs.  of  raw  material.  This  gas  may  be  first  absorbed  by 
water,  as  in  the  manufacture  of  sugar,  or  sulphur  dioxide 
may  be  used  instead  of  nitrous  gas.  The  former  would  be 
obtained  by  burning  about  7  ozs.  of  sulphur  for  every  88 
Ibs.  of  raw  material. 

The  material,  after  this  treatment,  is  washed.  Those  por- 
tions intended  for  the  production  of  isinglass  substitute  are 
freed  from  their  outer  skins  and  dried  and  pressed  at  a 
gentle  heat.  The  portions  destined  to  produce  gelatine  or 
glue  are,  on  the  contrary,  exposed  to  a  temperature  of  from 
104°  to  122°  F.  for  from  ten  to  twelve  hours,  by  which  the 
material  is  mainly  dissolved.  The  mass  is  then  forced 
through  a  strainer  or  sieve,  and  the  liquor  allowed  to  gela- 
tinize by  standing  for  some  hours.  The  jelly  is  finally 
dried,  as  is  usual  in  the  manufacture  of  glue  or  gelatine. 

Whale  glue  is,  according  to  Culmann,  obtained  in  the 
Russian  island  Jeretike  from  the  liquor  remaining  in  the 
boilers  after  the  extraction  of  the  oil  by  means  of  super- 
heated steam.  By  reason  of  the  raw  and  moist  atmosphere 
which  prevails  in  that  locality,  even  in  summer,  drying  the 
glue  is  not  practicable,  and  for  this  reason  it  is  brought 
into  commerce  in  the  form  of  a  compact  jelly  mixed  with  a 
preservative  and  packed  in  tin  boxes.  The  commercial 
article  contains  41.65  per  cent,  water.  It  is  liquefied  by 
placing  the  can  in  boiling  water,  and  melts  at  176°  F.  As 
shown  by  mechanical  tests,  it  possesses  great  tenacity,  and 
two  pieces  of  wood  glued  together  lengthwise  cannot  be 
separated  at  the  joint  but  break  alongside  of  it. 


CHAPTER  XI. 

TESTING  GLUE  AND  GELATINE. 

IT  is  of  importance  that  the  manufacturer  as  well  as  the 
dealer  should  know  how  to  test  the  quality  of  a  glue.  This 
may  be  done  by  chemical  means  and  in  a  mechanical  way. 

Determination  of  moisture.  For  this  purpose  a  weighed 
quantity  of  the  sample,  finely  powdered,  is  for  fourteen 
hours  exposed  to  a  temperature  of  217°  to  230°  F.  It  is 
then  cooled  under  the  dessicator  and  reweighed.  The  con- 
tent of  moisture  is  then  calculated  from  the  loss  in  weight. 

Determination  of  ash.  The  origin  of  a  sample  of  glue 
may  be  traced  by  examining  the  ash  for  phosphates  of  lime 
and  magnesia,  bone-glue  containing  both,  while  skin-glue 
is  free  from  phosphates.  Reduce  a  portion  of  the  sample 
to  a  fine  powder,  and  weigh  it  in  a  tared  constant  crucible. 
Heat  slowly  over  a  Bunsen  flarne  until  carbonized,  then 
remove  the  crucible  to  the  muffle,  and  heat  to  bright  red- 
ness for  10  hours.  Cool  under  the  dessicator  and  weigh. 
The  increase  in  weight  of  the  crucible  is  the  ash  of  the 
sample.  This  will  vary  from  1  to  2  per  cent,  in  a  gelatine, 
2  to  3  per  cent,  in  a  good  glue,  6  to  8  per  cent,  in  a  com- 
mon quality. 

Determination  of  Acidity.  Kistling  determines  the  acidity 
by  suspending  30  grammes  of  the  sample  in  80  Cc.  of  cold 
water  for  10  to  12  hours  in  a  flask  connected  with  a  con- 
denser. The  volatile  acids  are  then  driven  over  by  a  cur- 
rent of  steam  into  a  graduated  cylinder.  When  the  distil- 
late amounts  to  200  Cc.,  distillation  is  interrupted,  and  the 
distillate  treated  with  standard  decinormal  alkali.  When 
the  distillate  contains  sulphurous  acid,  a  known  quantity  of 
the  standard  alkali  is  previously  added  to  the  cylinder. 

( 205 ) 


206  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Aii  undue  quantity  of  acid  may  be  detected  by  the  taste. 
Glues  may  be  alkaline  from  the  addition  of  excess  of  lime 
in  the  manufacture  to  correct  the  sourness  of  the  jelly.  For 
uses  where  colors  are  concerned  the  glue  must  be  neutral  to 
litmus ;  for  adhesive  uses  this  does  not  matter  unless  the 
alkalinity  or  acidity  is  due  to  defective  preparation  (Samuel 
Rideal). 

Determination  of  Glutin.  The  percentage  of  glutin  in  a 
glue  solution  is  determined  by  precipitating  it  with  tannin. 
The  dense  white  precipitate  formed  is  thrown  on  to  a  tared 
filter,  washed  with  hot  water,  dried  and  weighed.  The 
calculation  is  made  on  the  basis  that  the  tannate  of  glutin 
has  a  percentage  composition  of  42.74  per  cent,  of  glutin 
and  57.26  per  cent,  of  tannin. 

Bisler-Beumat  while  employing  the  same  principle  pre- 
pares two  solutions  :  a.  10  grammes  of  pure  tannin  to  the 
liter,  b.  10  grammes  of  pure  isinglass  and  20  grammes  of 
alum  to  the  liter.  The  ratio  in  which  the  tannin  is  pre- 
cipitated by  the  isinglass  solution,  which  Risler  considers  as 
pure  glutin,  is  then  determined  by  titration.  The  tannin 
solution  is  then  diluted  so  that  exactly  an  equal  volume  of 
glue  solution  is  precipitated  by  it. 

In  order  to  test  a  sample  of  glue,  dissolve  10  grammes  of 
it  together  with  20  grammes  of  alum  in  a  liter  of  water, 
heat  being  applied  if  necessary.  Next  10  cubic  centimeters 
of  the  tannin  solution  are  taken  to  which  an  equal  bulk 
of  glue  solution  is  at  once  added,  as  one  may  be  sure 
that  this  quantity  is  not  sufficient  for  the  precipitation  of 
the  measured  quantity  of  tannin,  because  no  glue  found  in 
commerce  is  as  pure  as  isinglass.  The  vessel  containing 
the  mixed  liquids  being  well  shaken  and  the  precipitate 
having  subsided,  another  cubic  centimeter  of  glue  solution 
is  added  to  the  tannin  solution  which  is  next  filtered 
through  a  moist  cotton  filter.  If  one  drop  of  the  glue  solu- 
tion still  produces  a  precipitate  in  the  clear  filtrate,  another 
cubic  centimeter  is  added  to  the  tannin  solution,  and  then 


TESTING    GLUE    AND    GELATINE.  207 

again  filtered,  these  operations  being  repeated  until  the  fil- 
trate is  no  longer  rendered  turbid  by  the  glue  solution. 

With  the  known  relation  of  the  tannin  solution  to  pure 
glue  (isinglass),  a  conclusion  may  be  formed  from  the  num- 
ber of  cubic  centimeters  of  glue  solution  used  as  to  the  con- 
tent of  glutin  in  the  sample  examined. 

The  percentage  of  glutin  varies,  of  course,  according  to 
the  quality  and  origin  of  the  glue.  Bone  glue  of  good 
quality  contains  from  50  to  52  per  cent,  and  skin  glue  from 
65  to  75  per  cent. 

S.  Dana  Hayes  analyzed  two  samples  of  American  glue 
of  best  quality  and  obtained  the  following  results : 

a.  b. 

Water  (escaping  at  212°  F. ) 16.70  16.28 

Glue  substance 79.85  80.42 

Calcium  carbonate 1.42  1.33 

Calcium  sulphate     .    .    .    .  , 0.41  0.34 

Magnesium  phosphate 0.35  0.31 

Alkaline  salts 0.17  0.12 

Silica,  ferric  oxide,  etc 0.09  0.08 

Zinc  oxide 1.01  1.12 

The  chemical  modes  of  testing  glue  give  only  the  quan- 
tity of  glutin  contained  in  it,  but  do  not  prove  that  the  sub- 
stance combined  with  tannin  corresponds  to  the  actual 
adhesive  power  of  the  glue,  for  it  is  possible  that  a  glue 
containing  a  large  quantity  of  glutin  may  possess  but  little 
adhesive  power,  and  a  jelly  from  which  the  glue  is  formed 
may  contain  an  equal  amount  of  glutin  with  the  latter,  but 
not  possess  an  equal  power  of  adhesion. 

It  is  certain  that  the  determination  of  the  glutin  alone  is 
not  a  criterion  of  the  quality  of  glue.  In  the  absence  of  a 
reliable  method  of  direct  analysis,  attempts  have  been  made 
to  deduce  the  quality  of  glue  from  indirect  properties. 

One  of  these  methods  consists  in  immersing  the  sample 
of  glue  in  a  large  quantity  of  water  at  59°  F.  for  a  consider- 
able time.  The  glue  swells  up,  absorbing  5  to  16  times  its 


208  GLUE,    GELATINE,    CEMENTS,    PASTES. 

own  weight  of  water.  The  more  consistent  and  elastic  the 
glue  in  this  state  is  found  to  be,  the  greater  its  adhesive 
power,  and  the  larger  the  quantity  of  water  absorbed  the 
more  economical  the  glue  will  be  in  use.  This  method 
does  not  give  thoroughly  reliable  results,  and  should  only 
be  employed  with  bone-glue,  as  skin-glue  does  not  behave 
in  a  similar  manner. 

A  more  reliable  method  is  to  test  the  strength  of  a  glue 
by  the  method  first  proposed  by  Lipowitz,  which  is  based 

FIG.  65. 


on  the  weight-sustaining  power  of  a  jelly  of  known  strength 
and  temperature.  The  test  is  executed  as  follows :  Soak  5 
parts  of  the  sample  in  water,  then  dissolve  it  in  sufficient 
hot  water  to  make  the  weight  of  the  solution  equal  to  50 
parts,  and  allow  to  stand  for  12  hours  at  64.4°  F.  in  a  glass 
cylinder  of  uniform  width  to  gelatinize.  Cover  the  glass 
cylinder  with  a  tin  cap  perforated  in  the  centre,  Fig.  65. 
Through  the  perforation  is  passed  freely  a  stout  iron  wire, 
at  the  lower  end  of  which  is  soldered  a  piece  of  tin  shaped 


TESTING    GLUE    AND    GELATINE.  209 

like  a  saucer,  the  convex  side  of  it  resting  on  the  surface  of 
the  jelly.  To  the  upper  end  of  the  wire,  which  together 
with  the  tin  saucer  should  weigh  5  grammes,  is  soldered  a 
funnel  weighing  5  grammes,  and  capable  of  holding  up  to 
50  grammes  of  fine  shot.  The  apparatus  is  gradually 
loaded  with  shot  until  the  saucer-shaped  piece  of  tin  is 
forced  into  the  jelly.  The  greater  the  strength  of  the  jelly, 
the  heavier  will  be  the  weight  required.  From  the  deter- 
mined weight  of  the  shot  used,  the  relative  value  of  the 
glue  as  to  its  adhesive  power  is  determined. 

The  following  results  have  been  obtained  by  comparative 
experiments  with  this  apparatus  : 

Variety  of  Glue.  Weight  required  to  force 

the  saucer  down. 

Breslau 1704  grammes  =  3.74    Ibs. 

Kussian 1446  grammes  =  3.18    Ibs. 

Cologne  .  1215  grammes  ==  2.67    Ibs. 

Muhlhausen  1 727  grammes  =  1.599  Ibs. 

Nordlingen 724  grammes  =  1.592  Ibs. 

Muhlhausen  II 387.5  grammes  =  0.85    Ibs. 


The  results  of  these  experiments  agree  to  a  remarkable 
degree  with  the  market  prices  of  the  varieties  of  glue,  which 
is  not  the  case  with  glues  tested  by  the  methods  previously 
mentioned.  The  results  of  these  tests  are  given  in  the 
table  below : 
14 


210 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


Q) 

"5kg  <d 

j- 

fjSg 

*8]3«* 

O 

-S-s  § 

A  100  per  cent,  solution 

Variety  of  Glue. 

t2^ 

& 

<i  g'S) 

of  glue  will  bear  a 

'~o  &> 

•g  2  § 

P, 

03  3*0 

weight  of 

•"  30* 

as 

£ 

HJ3.2 

|ts3 

gS* 

3 

|a& 

1.  Best    White    isinglass   in    three 

qualities   

20  to  21 

74.62 

55.69 

2.  Translucent  yellowish  bone  glue 
in  tablets  and  easily  soluble  . 

13.2 

76.2 

58.8 

40 

64  grammes  (2.25  ozs.) 

3.  Pale  yellow  glue  similar  to  No.  2. 
4.  Brown-reddish,  brittle  in  fracture 

13.0 

70.0 

52.2 

35 

60  grammes  (2.11  ozs.) 

and  soluble 

10.0 

71.0 

52.9 

12 

Does  not  gelatinize. 

5.  Clear  translucent  glue  of  medium 

brown  color 

11.0 

71.5 

53.3 

20 

20  grammes  (0.705  oz.  ) 

6.  Brown-yellow  glue  in  thick  tab- 

lets and  possessing  but  little 

translucency   .             .... 

12.5 

68.0 

50.7 

27 

15  grammes  (0.52   oz.) 

7.  Pale  brown-yellow  glue,  readily 

soluble     and     elastic    before 

breaking 

13.0 

66.6 

49.7 

30 

36  grammes  (1.26   oz.  ) 

8.  Pale  amber-colored  glue  with  but 

little  translucency  
9.  Brown  glue,  solution  turbid  .  .  . 

9.5 
10.0 

68.5 
82.0 

51.1 
53.7 

33 
30 

«0  grammes  (2.11    oz.) 
5i)  grammes  (1.76   oz.) 

10.  Amber-colored     glue,    opalizing 

and  readily  soluble  
11.  Thick  tablets  of  dark-brown  glue, 

9.5 

73.0 

54.4 

35 

56  grammes  (1.97   oz.) 

solution  very  turbid       .... 

13.5 

64.0 

47.7 

18 

23  grammes  (0.81   oz.) 

12.  Dark  horn-like  glue  with  little 

translucency 

9.0 

72.6 

54.2 

29 

12  grammes  (0.42   oz.  ) 

13.  Very  translucent  glue  of  a  light 

brown  color  and   very  clean 

solution  

13.5 

70.0 

52.2 

30 

40  grammes  (1.41    oz.) 

14.  Translucent    dark-brown    glue, 

giving  a  very  clear  solution    . 

15.0 

66.0 

49.4 

25 

42  grammes  (1.48   oz.) 

This  table  shows  the  following  facts : 

I.-  The  percentage  of  water  in  the  14  dry  varieties  of  glue 
examined  varies  between  9.0  and  21.  The  loss  of  water 
from  isinglass  is  surprisingly  large,  especially  as  it  cannot 
be  explained  by  an  artificial  admixture  of  water,  since  the 
six  varieties  examined  reabsorbed  the  same  percentage  of 
water  from  the  air.  The  percentage  of  water  in  the  other 
varieties  of  glue  differs  but  little. 

2.  The  various  varieties  of  glue  required  different  quan- 
tities of  tannic  acid  for  their  precipitation,  the  amount  for 
100  parts  of  glue  varying  between  66  parts  and  76.2,  or 
calculated  to  per  cent.,  between  49.4  and  56.8. 

3.  Placed    in    cold   water,  glue   swells  up   and    absorbs 
from  12  to  40  parts  of  water.     The  behavior  of  the  various 
varieties  differs  very  much  in  this  respect,  and  in  most  of 


TESTING    GLUE    AND    GELATINE.  211 

the  experiments,  with  the  exception  of  variety  No.  4,  the 
percentage  of  glutin  is  in  exact  proportion  to  the  quantity 
of  water  absorbed. 

4.  The  strength  of  the  gelatinized  glue  varies  between  12 
grammes  (185.18  grains)  and  64  grammes  (987.67  grains) 
for  a  10  per  cent,  solution.  This  property  corresponds 
neither  with  the  absorption  of  water  nor  the  percentage  of 
glutin. 

Variety  No.  4,  in  the  table,  contains  52  per  cent,  of 
glutin,  but  does  not  gelatinize,  its  strength  being  therefore 
equal  to  0,  while  variety  No.  14,  with  49.4  per  cent,  of 
glutin,  therefore  less  than  No.  4,  shows  a  strength  of  42. 
As  no  close  connection  between  the  properties  mentioned  in 
the  table  can  be  recognized,  it  is  best  not  to  be  guided .  by 
these  properties  alone,  but  to  test  also  the  behavior  of  the 
glue  in  practical  use.  Such  test  consists  in  estimating  the 
adhesive  power  of  the  glue  from  the  weight  required  to  tear 
asunder  two  pieces  of  wood  glued  together  and  dried.  But 
as  the  results  obtained  by  this  purely  practical  test  must 
necessarily  vary  on  account  of  the  impossibility  of  having 
two  surfaces  of  wood  always  exactly  alike,  and  the  uncer- 
tainty of  applying  every  time  the  same  quantity  of  glue, 
Weidenbusch's  method  may  here  be  given.  It  is  based 
upon  the  principle  that  sticks  of  plaster  of  Paris  cast  of 
exactly  the  same  material  and  of  uniform  size  break  under 
the  same  weight  when  placed  upon  two  supports  and  loaded 
in  the  centre.  If  now  such  plaster  sticks  be  saturated  with 
glue  solutions  prepared  according  to  the  same  method,  but 
from  different  qualities  of  glue,  a  greater  force  will  be 
required  for  breaking  them,  and  this  force  will  be  the 
greater  the  better  the  quality  of  glue  is. 

The  plaster  sticks  are  prepared  as  follows :  Reduce  pure 
crystallized  gypsum  to  a  fine  powder,  pass  the  latter  through 
a  sieve  having  324  meshes  per  square  centimeter  and  heat 
it  to  between  284°  and  302°  F.  For  casting  the  sticks 
moulds  of  soap-stone  are  used.  The  moulds  are  made  by 


212 


GLUE,    GELATINE,    CEMENTS,    PASTES. 


boring  in  a  piece  of  soap-stone,  at  a  distance  of  about  1 
centimeter  from  each  other,  holes  with  a  diameter  of  6 
millimeters  on  top  and  7J  millimeters  on  the  bottom. 

The  gypsum  is  weighed  off  in  portions  of  1  gramme  each, 
mixed  with  1  gramme  water  and  cast  in  the  moulds.  The 
solidified  sticks  are  first  dried  at  a  moderate  heat  and  then 
over  calcium  chloride,  and  kept  for  use  in  an  air-tight 


FIG.  66. 


The  glue  solution  is  prepared  as  follows  :  The  glue  dried 
at  212°  F.  is  weighed,  soaked  over  night  in  water,  then 
melted  in  a  small  glass  in  the  water-bath,  and  finally 
enough  water  is  added  so  that  the  solution  contains  10  per 
cent  of  dry  glue. 


TESTING    GLUE    AND    GELATINE.  213 

The  plaster  sticks  are  for  one  or  two  minutes  immersed 
in  the  glue  solution  heated  to  212°  F.,  and  then  placed 
vertically  upon  a  glass  plate  until  superficially  dry,  when 
they  are  completely  dried  at  212°  F.  It  is  recommended 
to  color  the  glue  solution  with  indigo,  the  uniform  satura- 
tion of  the  sticks  being  thereby  more  easily  recognized. 

The  apparatus  for  testing  the  strength  of  the  sticks  con- 
sists of  a  brass  ring  a,  Fig.  66,  having  two  notches  to  re- 
ceive the  stick,  and  its  diameter  is  divided  into  two  equal 
parts  by  an  indicator.  The  ring  is  supported  by  a  pin,  by 
means  of  which  it  is  secured  in  a  stand.  The  apparatus  is 
completed  by  an  iron  or  glass  cup  which  is  suspended  by 
three  cords,  i,  and  the  hook  /  to  the  plaster  stick  6.  The 
hook  /  is  placed  in  the  position  indicated  by  the  indicator, 
Mercury  is  now  poured  into  the  cup  until  the  plaster  stick 
commences  to  break.  The  weight  required  is  recorded  and 
compared  with  a  standard  glue.  During  the  experiment 
the  cup  is  suspended  by  the  three  cords  h  to  the  ring  a,  and 
is  thus  caught  when  the  plaster  stick  breaks.  On  the  lower 
end  of  the  cup  is  a  clip  for  emptying  the  mercury  into  a 
vessel  so  that  none  of  it  is  lost. 

The  "  Artillery  Werkstatte  "  at  Spandau  has  adopted  the 
severing  strain  of  two  blocks  of  wood  glued  together.  The 
test  is  executed  as  follows  :  Three  parts  of  glue  (but  not  less 
than  250  grammes)  are  mixed  with  6  parts  of  water  and 
boiled  in  a  steam  bath  until  the  weight  of  the  boiled  glue 
amounts  to  only  f  of  the  original  mixture.  The  reason  for 
this  continued  boiling  is  to  ascertain  whether  the  glue  to  be 
tested  retains  the  required  adhesive  power  even  after  six 
hours  continued  heating  in  a  steam  bath  as  frequently  hap- 
pens in  the  workshop.  With  the  glue  thus  prepared  the 
following  breaking  test  is  made  : 

Blocks  of  hard  or  soft  wood  420  millimeters  long  and 
40  x  40  millimeters  cross  section  are  cut  in  two,  so  that  each 
piece  thus  obtained  is  210  millimeters  in  length.  These 
two  pieces  are  then  again  glued  together  across  the  grain 


214  GLUE,    GELATINE,    CEMENTS,    PASTES. 

with  the  glue  to  be  tested.  The  block  is  then  placed  in  a 
dry  room  at  a  temperature  of  62°  to  68°  F.  for  72  hours, 
when  the  joint  is  tested  as  to  its  resisting  power.  At  a  dis- 
tance of  180  millimeters  from  the  joint  a  hole  is  bored  in 
the  block.  Through  this  hole  is  pushed  a  bolt  furnished 
on  the  lower  end  with  a  hook  to  which  a  scale  is  suspended. 
The  block  of  wood  is  clamped  to  a  table  so  that  the  joint 
projects  1  centimeter  beyond  the  edge.  The  scale  is  at  the 
start  loaded  with  25  kilograms,  the  load  being  every  five 
minutes  increased  5  kilograms  till  fracture  takes  place. 

Two  such  blocks,  one  of  hard  and  one  of  soft  wood,  are 
subjected  to  the  test,  and  a  serviceable  glue  must  stand  at 
least  an  average  load  of  70  kilograms. 

Determination  of  adulterations.  White  lead,  sulphate  of 
lead,  zinc  white,  or  chalk  in  quantities  varying  from  4  to 
8  per  cent,  are  frequently  mixed  with  the  melted  glue  to 
improve  the  appearance  of  the  finished  product.  Thus, 
according  to  analyses  by  A.  Faisst,  Russian  glues  contained 
in  100  parts  foreign  admixtures  as  follows : 

I.  II.  III.  IV. 

Zinc  white 1.66 

Chalk ''••••    2-40  2.95  3.79  2.10 

Sulphate  of  lead —  4.16  2.35  3.18 

4.06        7.08        6.14         5.28 

The  so-called  patent  glue  which  is  opaque  and  of  a  white 
color  is  produced  by  adding  considerable  quantities  of  white 
lead  to  ordinary  glue. 

According  to  Barreswil,  glue  is  frequently  mixed  with 
lead  acetate  solution  to  protect  it  from  putrefaction.  Such 
an  addition,  as  well  as  the  presence  of  white  lead  or  sul- 
phate of  lead,  is  detected  by  the  introduction  of  sulphuretted 
hydrogen  into  very  dilute  glue  solution.  In  the  presence 
of  lead  acetate  a  black  precipitate  of  lead  sulphide  appears 
in  the  clear  solution  ;  if  white  lead  or  lead  sulphate  is  pre- 
sent, the  white  powder  settling  on  the  bottom  is  blackened 
by  the  formation  of  lead  sulphide. 


TESTING   GLUE    AND    GELATINE. 


215 


For  the  detection  of  other  earthy  additions,  prepare  a 
very  dilute  solution  of  the  glue  in  question  and  allow  it  to 
stand  quietly  for  a  few  hours.  The  heavy  additions  sub- 
side, and  after  decanting  the  supernatant  fluid  is  collected 
upon  a  small  filter  and  examined  by  the  customary  analyt- 
ical methods. 

It  is  difficult  to  say  what  quantities  of  earthy  constituents 
actually  constitute  an  adulteration,  since  it  is  claimed  by 
many  practical  men  that  a  considerable  content  of  earthy 
parts  is  of  advantage  as  regards  the  cementing  power  of 
glue.  Generally  speaking  it  may,  however,  be  said  that 
a  glue  containing  more  than  6  to  8  per  cent,  of  earthy  con- 
stituents must  be  considered  adulterated. 

For  many  purposes,  especially  if  the  glue  comes  in  con- 
tact with  colored  materials  as,  for  instance,  in  book-binding, 
a  content  of  free  acid  would  exert  an  injurious  effect  upon 
the  colors,  destroying  or  changing  them.  It  is  therefore 
advisable  to  test  the  glue  with  blue  litmus  paper  which,  in 
the  presence  of  free  acid,  is  reddened. 

In  testing  a  large  number  of  samples  of  glue,  Kissling 
obtained  the  following  results  : 


SKIN  GLUE.                   of 
WTater     

Number 
'  samples. 
15 
16 
21 

8 

25 
26 
5 

7 

Smallest 
percentage. 
13.4 
1.0 
0.01 
f  0.084 
1  0.084 

11.5 
1.16 
0.047 
f  0.088 
10.097 

Largest 
percentage. 
18.1 
4.13 
0.090 
0.238 
0.334 

17.7 
507 
0.217 
1.451 
0.721 

Average 
percentage. 
15.7 
2.15 
0.037 
0.178 
0.191 

13.4 
2.46 
0.113 
0.655 
0.460 

Ash     

Fat    

Volatile  acids,  free  .    .  \ 
Volatile  acids,  fixed  .  .  / 
BONE  GLUE. 
Water 

Ash  
Fat   
Volatile  acids,  free  .    .  \ 
Volatile  acids,  fixed  .  .   / 

However,  those  who  from  their  practical  knowledge  are 
most  competent  to  judge  the  commercial  value  of  a  glue, 
scarcely  require  such  complicated  tests,  as  by  taking  the 


216  GLUE,    GELATINE,    CEMENTS,    PASTES. 

sample  in  their  hand  and  looking  at  it,  they  can  in  most  cases 
tell  its  quality.  Great  hardness,  a  clear,  rattling  sound  when 
struck,  and  resistance  to  breaking  are  signs  of  good  quality, 
and  if  the  cake  is  cut  thick,  it  shows  that  the  jelly  possessed 
great  consistency.  Many  kinds  of  glues  are  intentionally 
cut  thin  so  that  they  will  dry  before  spoiling.  The  deriva- 
tion of  a  glue  from  a  sound  jelly  is  recognized  by  the  fine 
cutting  lines.  When  the  jelly  possesses  but  little  gelatiniz- 
ing power  and  is  in  the  first  stages  of  decomposition  or 
putrefaction,  or  formation  of  sugar  has  already  set  in,  it  can- 
not be  poured  into  moulding  boxes,  as  it  would  putrefy  be- 
fore it  has  a  chance  to  gelatinize.  Such  sick  jelly  is  poured 
in  thin  layers  upon  glass  or  metal  plates  so  that  it  may 
acquire  sufficient  solidity  to  allow  of  its  being  cut  up  into 
leaves  and  dried  upon  nets.  If  the  edges  of  the  glue  are 
deeply  indented  and  raised,  the  jelty,  before  drying,  pos- 
sessed but  little  concentration  (25  to  30  per  cent.),  and  if 
notwithstanding  this,  it  acquired  sufficient  consistency  to 
allow  of  its  being  cut,  it  must  have  been  very  sound. 
Glues  cut  thick  and  showing  no  indentations  and  raised 
edges,  are  derived  from  excessively  concentrated  jellies 
(30-35-40  per  cent.).  Such  jellies  lose  in  quality  in 
evaporating. 

A  high  degree  of  transparency  is  a  favorable  sign  as  re- 
gards the  purity  of  a  glue,  substances  inducing  putrefaction 
having  been  eliminated.  Hence  this  property  should  be 
worthy  of  recommendation,  but  the  consumer  having  been 
disappointed  in  the  use  of  thin  glass-clear  glues,  distrusts 
also  the  thick-cut  transparent  product,  preferring  a  turbid, 
translucent  or  opaque  article.  For  this  reason  the  manu- 
facturer is  forced  to  render  glass-clear  glue  turbid  with  col- 
oring matter. 

The  color  of  the  glue  is  also  a  means  of  judging  it.  To 
be  sure,  chemically  pure  glutin  is  a  colorless  substance,  but 
glue  is  always  colored  more  or  less  dark  brown.  Although 
this  coloration  does  not  in  the  least  impair  the  adhesive 


TESTING    GLUE    AND    GELATINE.  217 

power,  the  manufacturer  endeavors  to  produce  a  product  of 
as  light  a  color  as  possible,  and  this  is  best  effected  by 
bleaching  with  sulphurous  acid.  By  this  means  the  glue 
not  only  acquires  a  lighter  color,  but  also  becomes  more 
stable,  substances  inducing  putrefaction  being  destroyed  by 
the  acid. 


PART  II. 
CEMENTS,  PASTES,  MUCILAGES. 


CHAPTER  XII. 

CLASSIFICATION  OF  CEMENTS. 

THE  great  variety  of  substances  entering  into  the  manu- 
facture of  cements  and  pastes  makes  a  division  of  them 
extremely  difficult.  Stohmann  divides  them  into  the  fol- 
lowing groups : 

1.  Oil  cements. 

2.  Resinous  cements. 

3.  Cements  containing  rubber  or  gutta  percha. 

4.  Cements  containing  glue,  or  starch  paste. 

5.  Lime  cements. 

Generally  speaking,  this  division  is  correct;  the  only 
change  we  would  suggest  is  to  apply  the  term  agglutinant 
or  paste  to  bodies  containing  glue  and  starch  paste. 

When  we  attempt  a  division  of  the  cements  according  to 
the  bodies  to  be  cemented,  we  find  that  the  result  will  be  a 
larger  number  of  groups ;  as  we  must  take  into  considera- 
tion whether  the  articles  to  be  cemented  have  to  be  heated 
or  not,  whether  they  are  to  come  in  contact  with  water  or 
other  liquids,  and  other  circumstances  which  would  neces- 
sitate modifications  in  the  composition  of  the  cements 
themselves. 

According  to  this,  we  might  group  the  cements  as  fol- 
lows : 

1.  Cements  for  glass  and  porcelain,  for  repairing  broken 

(218) 


CLASSIFICATION    OF    CEMENTS.  219 

articles,  for  fastening  glass  letters  upon  sliow-windows, 
etc. 

2.  Cements  for  metals  not  exposed  to  an  increase  of  tempera- 

ture, for  instance,  for  tightening  the  joints  of  gas  and 
water  pipes. 

3.  Cements  for  stoves  and  other  articles,  which  have  to  stand 

an  increased  temperature. 

4.  Cements  for  chemical  apparatus,  i.  e.,  such  as  will  have  to 

resist  the  action  of  chemical  agents. 

5.  Cem.ents  to  protect  vessels  of  glass,  porcelain,  or  metal 

against  the  action  of  fire. 

6.  Cements  for  filling  hollow  teeth,  for  microscopical  prepara- 

tions, and  other  delicate  articles. 

7.  Cements  for  special  purposes,  for  instance,  for  cementing 

meerschaum,  tortoise  shell,  etc. 

Chemical  nature  of  cements.  The  different  varieties  of 
cement  frequently  contain  substances  which  act  chemically 
upon  each  other,  or  upon  the  bodies  to  be  united  with  them. 
To1  determine  the  practical  availability  of  a  variety  of 
cement  for  a  determined  purpose,  it  is  of  importance  to 
know  the  reciprocal  behavior  of  these  substances  towards 
each  other,  as  from  this  we  are  able  to  judge  at  once 
whether  a  cement  is  suitable  for  a  certain  purpose  or  not. 

Oil  cem.ents.  The  fluid  fats,  commonly  called  oils — 
though  there  are  oils  which  remain  solid  at  the  ordinary 
temperature,  as,  for  instance,  palm  oil  and  cocoanut  oil — 
may,  as  regards  their  behavior  on  exposure  to  the  air,  be 
divided  into  two  large  groups,  namely,  drying  and  non- 
drying  oils.  As  samples  of  these  groups  may  be  mentioned 
olive  oil  and  linseed  oil. 

If  a  thin  layer  of  olive  oil  protected  from  dust  is  exposed 
to  the  air,  it  will  remain  fluid  for  years  and  retain  its  char- 
acteristic oily  consistency.  The  only  change  it  undergoes 
is  that  it  becomes  somewhat  more  viscid  and  rancid,  and 
acquires  a  darker  color,  but  it  never  dries  up. 

Linseed  oil  treated  in  the  same  manner  solidifies  in  the 


220  GLUE,    GELATINE,    CEMENTS,    PASTES. 

course  of  a  few  weeks  to  a  hard,  tough  and  elastic  mass,  re- 
sembling, as  regards  its  physical  qualities,  resin  or  rubber. 

By  compounding  a  drying  oil  with  a  small  quantity  of 
litharge,  pyrolusite,  manganous  borate,  etc.,  and  heating 
the  admixture  to  the  boiling-point,  it  acquires  the  property 
of  drying  in  a  few  hours  when  exposed  to  the  air  in  a  thin 
layer.  Oil  so  treated  has  been  changed  to  a  varnish. 

By  bringing  a  drying  oil  in  contact  with  a  body  posses- 
sing strong  basic  properties  a  peculiar  process  takes  place ; 
the  sebacic  acids  contained  in  the  oil  combine  with  the 
basic  bodies  to  solid  combinations  which  are  insoluble  in 
water,  and,  on  exposure  to  the  air,  change  gradually  into 
masses  as  hard  as  stone.  Such  combinations,  as  regards 
their  chemical  composition,  resemble  ordinary  soap,  and  for 
this  reason  are  called  insoluble  soaps  to  distinguish  them 
from  ordina^  soap  which  is  soluble  in  water. 

Burned  lime,  calcined  magnesia,  whiting,  ferric  oxide, 
litharge,  and  minium  possess  the  capacity  for  forming  in- 
soluble soaps  on  coming  in  contact  with  drying  oils  and, 
still  more  quickly,  with  varnishes  prepared  from  them. 

The  hardness  of  these  soaps  in  time  increases  considerably 
by  the  oil  not  saponified  drying  in.  The  oil  cements  are 
principally  used  for  tightening  water  and  gas  pipes,  as  they 
resist  the  action  of  water,  steam  and  gas. 

The  only  drawback  connected  with  these  cements  is  that 
they  must  reach  a  certain  age  before  becoming  entirely  hard, 
and  that,  on  account  of  the  high  price  of  drying  oil  or 
varnish  which  is  absolutely  required  for  their  preparation, 
they  are  rather  expensive.  The  ordinary  glazier's  putty  and 
the  red  lead  and  linseed-oil  cement  used  in  constructing 
water  and  gas  conduits  belong  to  this  group. 

Resinous  cements.  By  resins  are  understood  a  number  of 
constituents  of  plants  which  exude  in  thick  viscous  masses 
through  incisions  made  in  the  trees,  and  on  exposure  to  air 
are  gradually  converted  into  less  transparent,  brittle  masses. 
When  heated  they  melt  more  or  less  readily,  forming  a 


CLASSIFICATION    OF    CEMENTS.  221 

thick,  ropy  liquid,  and  brought  in  contact  with  an  ignited 
body  they  burn  with  a  bright  flame  and  much  sooty  smoke. 
By  making  incisions  in  the  bark  of  any  of  the  whole 
genus  of  Pinus  belonging  to  the  Coniferce  family,  a  viscous 
mass  of  a  strong  odor,  called  turpentine,  is  obtained.  It 
consists  of  a  solution  of  common  rosin  in  the  essential  oil  of 
turpentine,  and  when  distilled  yields  from  75  to  90  per 
cent,  of  colophony  or  rosin,  which  remains  in  the  retort, 
and  from  25  to  10  per  cent,  of  the  essential  oil,  commonly 
called  spirits  of  turpentine.  Pure  rosin  is  a  brittle,  taste- 
less, and  almost  inodorous  mass  of  a  light  yellow  color  and 
a  smooth,  shining  fracture. 

The  various  resins  found  in  commerce,  such  as  shellac, 
mastic,  elemi,  copal,  etc.,  are  formed  in  a  similar  manner. 

The  principal  points  of  importance  for  our  purpose  are 
the  different  degrees  of  hardness  and  brittleness  and  the 
melting-points  of  the  various  resins.  While  some  possess 
but  slight  hardness,  for  instance  elemi,  others,  such  as  copal 
and  amber,  excel  in  this  respect  and  their  brittleness  and 
high  melting-point. 

To  decrease  the  brittleness  of  resins,  essential  oils  are 
sometimes  added,  or  resinous  cements  are  mixed  with  oil 
cements  or  a  fat  drying  oil,  or  compounded  with  rubber 
cement. 

Resinous  cements  are  either  softened  by  heating  or  en- 
tirely melted,  or  solutions  of  resins  in  volatile  solvents  are 
used,  which,  in  evaporating,  leave  the  resin  behind. 

The  resinous  cements  possess  great  power  of  resistance, 
and  are  therefore  well  adapted  for  tightening  water  and  gas 
pipes,  but  they  have  the  disadvantage  of  not  standing  a 
high  temperature  and  possessing  a  certain  degree  of  brittle- 
ness  which  renders  them  unfit  for  the  cementing  of  articles 
exposed  to  frequent  shocks. 

Many  of  these  cements,  especially  those  prepared  with 
pitch  or  asphaltum,  can  be  produced  at  a  very  low  cost, 
and  do  excellent  service  for  water-proofing  vessels,  water- 
reservoirs,  brickwork,  etc. 


222  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Rubber  and  gutta-percha  cements.  Caoutchouc,  commonly 
called  India  rubber,  or  briefly  rubber,  is  derived  from  the 
milky  juices  of  certain  tropical  plants.  It  is  distinguished 
by  great  elasticity  and  indifference  to  chemical  agents. 

Both  these  properties  make  it  a  valuable  material  for 
cement,  and  it  is  much  used  for  this  purpose  either  in  the 
form  of  solution  or  as  a  constituent  of  other  compositions. 
For  cements  which  are  to  have  a  certain  degree  of  elasticity 
combined  with  indifference  toward  chemical  agents,  it  is 
absolutely  indispensable,  as  no  other  known  body  possesses 
these  properties  in  such  a  high  degree. 

The  derivation  of  gutta  percha  is  similar  to  that  of 
rubber.  At  an  ordinary  temperature  it  forms  solid  and 
very  tenacious  masses,  of  a  leather-like  consistency,  but  at 
a  somewhat  higher  temperature  (below  the  boiling-point  of 
water)  it  is  converted  into  a  very  plastic,  soft  mass,  which 
can  be  drawn  into  very  fine  threads,  and  rolled  to  very 
thin  plates. 

By  itself  or  mixed  with  other  substances  it  furnishes  an 
excellent  cement,  possessing  the  valuable  properties  of 
tenacity  and  pliancy  when  exposed  to  shocks.  As  regards 
resistance  to  the  action  of  water  and  chemical  agents  it  is 
almost  equal  to  rubber,  and,  for  certain  purposes,  is  fre- 
quently preferred  to  the  latter. 

Glue  and  starch  cements.  By  itself,  i.  e.,  converted  by 
boiling  with  water  into  a  viscous  mass  which  solidifies  on 
cooling,  glue  cannot  be  classed  with  the  cements  ;  the  same 
applies  to  paste,  i.  e.,  starch  or  flour  swelled  and  boiled  in 
water. 

But  compounded  with  other  substances  both  yield  excel- 
lent cements,  in  which  a  part  of  the  properties  distinguish- 
ing glue  solution  and  paste  is  preserved.  They  both 
possess  the  property  of  decreasing  the  brittleness  of  many 
cements,  but  unfortunately  the  latter  thereby  lose  their 
power  of  resisting  the  action  of  water ;  for  starch  as  well  as 
glue  swells  in  water,  and  the  latter,  when  moist,  passes 
quickly  into  putrefaction  and  destroys  the  cement. 


CLASSIFICATION    OF    CEMENTS.  223 

In  a  wider  sense  isinglass,  compounds  of  glue  and 
vinegar,  of  lime  and  glue,  etc.,  must  be  classed  with  the 
glue  cements,  and  ordinary  flour  and  shoemakers'  paste 
with  starch  cements. 

Lime  Cements.  Lime  possesses  the  property  of  forming 
insoluble  combinations  with  egg  albumen  or  caseine,  this 
being  the  reason  why  lime  cements,  of  which  there  are  a 
great  number,  are  generally  composed  of  burned  lime  and 
one  or  the  other  of  the  above  substances.  Lime  com- 
pounded with  a  solution  of  water-glass  forms  also  very 
solid  and  durable  cements. 

Although  the  cements  and  agglutinants  mentioned  in 
the  foregoing  are  most  frequently  used,  a  compound  of 
different  cements  is  often  employed,  in  consequence  of 
which  the  composition  of  many  cements  is  very  com- 
plicated. 

In  the  following  we  give  a  description  of  the  preparation 
of  the  different  kinds  of  cement,  according  to  the  manner 
of  their  employment. 


CHAPTER  XIII. 

PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES. 
OIL    CEMENTS. 

OIL  cements,  as  already  explained,  must  be  considered  as 
a  variety  of  soaps  insoluble  in  water,  formed  by  the  action 
of  drying  oils  or  varnish  upon  various  basic  combinations. 

The  most  important  of  this  class  is  the  cement  used  for 
securing  window-panes.  Good  glaziers'  putty  is  a  product 
of  extraordinary  durability,  and,  besides  for  puttying  glass 
and  wood,  can  also  be  used  for  joining  many  other  bodies. 

Putty.  This  is  prepared  by  mixing  fine  whiting  with 
linseed  oil  or  linseed-oil  varnisL  The  whiting  should  be 
passed  through  a  sieve  of  42  meshes  to  the  inch.  It  should 
be  perfectly  dry  before  sifting,  and  be  thoroughly  incorpo- 
rated with  the  oil. 

As  the  work  of  kneading  large  masses  with  the  hands  or 
feet  must  be  continued  for  a  long  time  in  order  to  obtain  an 
entirely  uniform  product,  and  is  consequently  very  labori- 
ous, it  is  recommended  to  use  the  following  contrivance : 

Two  wooden  rollers  rest  in  a  suitable  frame,  and  can  be 
brought  together  or  removed  from  each  other  by  means  of 
two  screws.  When  the  mixture  of  whiting  and  linseed  oil 
is  of  sufficient  consistency  to  allow  kneading,  it  is  fashioned 
into  a  cylinder  and  rolled  out  between  the  above  rollers  to 
a  long,  thin  band,  which  is  caught  in  a  vessel.  The  band 
is  balled  together,  the  ball  reformed  into  a  cylinder,  and 
the  latter  again  passed  through  the  rollers,  the  operation  of 
balling  and  rolling  being  continued  until  a  uniform  mass 
is  obtained. 

The  finished  product  should  be  kept  in  oiled  paper  or 

(224) 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       225 

under  water.  White  lead  is  sometimes  mixed  with  the 
putty,  and  other  pigments  to  give  color  as  desired.  Hard 
putty  may  be  softened  by  rolling  between  the  hands. 

French  putty.  Boil  7  Ibs.  of  linseed  oil  with  4  Ibs.  of 
burnt  umber  for  2  hours.  Then  add  10  Ibs.  of  white  lead 
and  5J  Ibs.  of  chalk. 

Soft  putty.  Whiting  20  Ibs.,  white  lead  2  Ibs.,  linseed 
oil  and  olive  oil  1  gill  each. 

Mix  the  whiting  and  the  white  lead  with  the  necessary 
quantity  of  linseed  oil,  to  render  the  putty  of  the  proper 
consistence,  the  olive  oil  being  added  to  the  linseed  oil  before 
kneading.  The  object  of  using  olive  oil  is  to  prevent  the 
white  lead  from  hardening,  and  it  preserves  the  putty  in  a 
state  sufficiently  soft  to  adhere  at  all  times,  and  not,  by  get- 
ting hard  and  cracking  off,  suffering  the  wet  to  enter,  as  is 
often  the  case  with  ordinary  hard  putty. 

Litharge  cement.  By  mixing  litharge  reduced  to  a  fine 
powder  with  linseed  oil,  a  yellow  cement  is  obtained  which 
gradually  solidifies  to  a  mass  as  hard  as  stone. 

Red  lead  cement  is  made  by  mixing  red  lead  with  linseed 
oil  to  a  paste.  It  is  used  for  cementing  the  joints  of  metal 
pipes. 

Lead  preparations  furnish  excellent  cements,  but  have 
the  disadvantage  of  great  weight  and  a  high  price.  For 
many  purposes  a  part  of  the  lead  combination  can  be  suit- 
ably replaced  by  a  substance  of  less  weight,  such  as  whiting, 
or,  still  better,  burned  lime  slacked  with  sufficient  water  to 
convert  it  into  a  powder. 

The  quantity  of  the  substitute  added  varies  very  much, 
there  being,  for  instance,  many  varieties  of  so-called  red  lead 
oil  cement,  which  contain  only  about  10  per  cent,  of  red  lead. 

Cement  for  wash  basins.  Finely  powdered  glass  (sifted)  2 
parts,  litharge  2  parts,  linseed-oil  varnish  1  part. 

Wet  the  powders  slightly  with  the  oil,  heat  and  gradually 
add  the  rest.  Do  not  use  the  basin  for  several  days.  Finely 
powdered  glass  or  glass  meal  may  be  made  by  heating  glass, 
15 


226  GLUE,    GELATINE,    CEMENTS,    PASTES. 

throwing  it  in  cold  water,  grinding  the  fractured  pieces,  and 
washing  by  stirring  up  in  water,  and  allowing  the  finer 
particles  to  float  off  into  a  second  vessel.  Collect  this  fine 
powder  when  sufficient  has  settled  in  the  vessel  and  sift  it 
through  a  very  fine  sieve. 

Zinc-white  cement  is  prepared  similar  to  putty  or  red-lead 
cement.  It  may,  however,  be  made  as  follows :  Mastic  2 
parts,  dammar  4  parts,  sandarac  6  parts,  Venetian  turpen- 
tine 8  parts,  turpentine  10  parts,  benzole  12  parts,  zinc 
white  14  parts. 

The  resins  are  powdered,  while  the  Venetian  turpentine, 
ordinary  turpentine,  and  benzole,  are  put  in  a  bottle,  and 
then  the  powdered  resins  put  in.  The  whole  is  shaken  and 
allowed  to  stand  for  the  resins  to  dissolve.  The  solution  is 
filtered  through  cotton-wool  and  rubbed  up  with  sufficient 
zinc-white  to  form  a  cement.  Dilute  with  benzine  if 
necessary. 

Mastic  cement,  mastic  or  pierres  de  mastic.  Under  this 
name  masses  are  brought  into  commerce  which  are  well 
adapted  for  moulding  ornaments,  such  as  figures,  columns, 
etc.,  to  be  exposed  to  the  weather.  They  are  comparatively 
cheap,  and  it  is  rather  remarkable  that  they  are  not  more 
generally  known  and  used  for  technical  purposes. 

To  prepare  large  quantities  of  this  cement  suitable  mills 
and  mixing  vessels  are  required,  as  the,  con  version  of  the 
materials  into  a  dust-like  flour  is  an  indispensable  condition 
of  the  success  of  the  work.  The  materials  most  generally 
used  are  fine  quartz  sand,  finely  ground  calcareous  sand, 
and  varying  quantities  of  litharge  or  zinc  oxides,  besides  as 
small  a  quantity  of  linseed  oil  as  possible. 

The  linseed  oil  combines  with  the  litharge  or  zinc  oxide 
to  an  insoluble  soap,  which  incloses  the  other  material  and 
forms  a  mass  acquiring  the  hardness  of  sandstone  in  thirty 
to  fifty  hours. 

After  converting  the  materials  into  a  fine  powder,  the 
mixing  is  accomplished  in  barrels  filled  about  three-quarters 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       227 

full  and  revolved  by  water-power.  When  a  thorough  mix- 
ture has  been  effected  the  pulverulent  mass  is  placed  in 
sheet-iron  vessels  and  saturated  with  linseed  oil,  and  then 
moulded  at  once,  as  it  solidifies  in  one  or  two  days. 

French  mastic.  Quartz  sand  300  parts,  pulverized  lime- 
stone 100,  litharge  50,  linseed  oil  35. 

Paget's  mastic.  Sand  315  parts,  whiting  105,  white  lead 
25,  calcined  red  lead  10,  lead  acetate  solution  45,  linseed 
oil  35. 

The  mastic  may  be  colored  by  adding  pigments. 

Waterproof  cement.  A.  Rubber  7  parts,  oil  of  turpentine 
140,  linseed  oil  40.  B.  Turpentine  100  parts,  sulphuric 
acid  3,  zinc-white  10. 

To  prepare  solution  A,  place  the  rubber  in  the  oil  of 
turpentine  in  a  bottle.  It  swells  very  much  without 
actually  dissolving.  After  adding  the  linseed  oil,  reduce 
the  entire  mass  by  boiling  to  one-half  the  volume  originally 
occupied  by  it. 

Solution  B  is  prepared  by  stirring  the  sulphuric  acid  into 
the  turpentine  and  allowing  it  to  stand  for  twelve  hours. 
To  remove  the  sulphuric  acid,  the  thick  mass  which  has 
been  formed  is  then  kneaded  in  water  in  which  the  zinc 
oxide  has  been  distributed.  After  drying,  the  resulting 
mass  is  dissolved  in  the  warm  fluid  A. 

Another  formula  is  as  follows  :  Linseed  oil  8  parts,  litharge 
12,  burnt  lime  88. 

Boil  the  linseed  oil  and  litharge  half  an  hour,  then  stir 
the  lime  into  the  hot  mass,  and  use  the  mixture  hot.  This 
cement  is  excellent  for  filling  in  joints  between  stones,  for 
flat  roofs,  water  reservoirs,  etc.  For  a  better  adhesion  of 
the  cement,  apply  a  coat  of  linseed  oil  varnish  to  the  sur- 
faces to  be  cemented.  Porous  stones  are  made  waterproof 
by  heating  the  cement  in  a  boiler  and  adding  sufficient 
linseed  oil  to  form  a  mass  which  can  be  readily  worked 
with  a  smoothing  board.  Apply  as  hot  as  possible. 

Serbat's  mastic.  Pyrolusite  60  parts,  sulphate  of  lead  60, 
linseed  oil  10. 


228  GLUE,    GELATINE,    CEMENTS,    PASTES. 

After  thoroughly  drying  the  materials,  mix  the  sulphate 
of  lead  with  the  linseed  oil,  then  add  20  parts  of  the  pyro- 
lusite  and,  after  mixing  and  working  it  thoroughly,  add 
gradually  the  rest  of  the  pyrolusite  in  small  portions  and 
kneading  constantly. 

Stephensoris  oil  cement.  Litharge  20  parts,  unslaked  lime 
10  parts,  sand  10  parts,  hot  linseed  oil  3  parts. 

Alum  cement.  Dissolve  good  hard  soap,  by  heating  in 
rain  water,  dilute  the  thickly  fluid  mass  and  add  saturated 
alum  solution  as  long  as  a  precipitate  is  formed.  Collect 
the  gelatinous  precipitate  of  alumina  soap  thus  formed 
upon  a  cloth,  and,  after  draining,  pour  rain  water  over  it 
ten  to  twelve  times  to  remove  the  salts  as  much  as  possible. 
After  washing,  dry  the  alumina  soap,  and  rub  it  to  a  fine 
powder. 

To  prepare  cement  rub  a  portion  of  the  powder  with 
sufficient  linseed-oil  varnish  to  form  a  plastic  dough,  which 
is  used  for  filling  in  the  joints. 

This  cement  is  waterproof,  resists  high  temperatures 
without  being  absolutely  fire-proof,  and,  on  account  of  its 
light  color,  is  well  adapted  for  joining  marble  plates,  etc. 

Oil  cement  for  glass.  Litharge  30  parts,  burnt  lime  20, 
pipe-clay  10,  linseed-oil  varnish  6. 

Oil  cement  free  from,  lead  for  steam  pipes.  Graphite  12 
parts,  heavy  spar  16,  slaked  lime  6,  boiled  linseed  oil  6. 

Oil  cements  for  steam  pipes.  I.  Litharge  25  parts,  air- 
slaked  lime  10,  quartz  sand  10. 

Mix  the  ingredients  quickly  with  the  linseed  oil  and 
work  the  mass  thoroughly  in  a  hot  mortar.  Coat  the  de- 
fective places  in  the  pipes  with  linseed-oil  varnish,  apply 
the  cement  hot  and  when  partially  solid,  make  it  still 
tighter  by  heating. 

II.  Boil  60  parts  of  graphite,  50  of  air-slaked  lime,  60  of 
elutriated  heavy  spar  in  35  of  linseed  oil,  stirring  con- 
stantly. Apply  the  mixture  hot. 

Oil  cement  for  marble.  Elutriated  litharge  10  parts, 
brick  dust  100,  linseed  oil  20. 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.      229 

Prepare  in  the  same  manner  as  glaziers'"  putty.  For 
various  colors  add  zinc  white  for  white,  red  lead  for  red, 
pyrolusite  for  brown,  etc.  Previous  to  applying  the  cement 
saturate  the  surfaces  of  the  stones  to  be  cemented  with  lin- 
seed-oil varnish. 

Oil  cement  for  porcelain.  Stir  20  parts  of  white  lead  and 
12  of  white  pipe-clay  into  10  of  boiling  linseed  oil  previously 
boiled  and  knead  the  mass  thoroughly.  After  cementing 
let  the  articles  stand  quietly  for  several  weeks. 

Diamond  cement.  Litharge  30  parts,  air-slaked  lime  10, 
whiting  20, -graphite  100,  linseed  oil  40.  Apply  hot.  This 
is  an  excellent  cement  for  metal. 

Hager's  diamond  cement.  Whiting  16  parts,  elutriated 
graphite  50,  litharge  16. 

Mix  the  pulverized  ingredients  with  sufficient  old,  thick 
linseed  oil  to  form  a  plastic  dough.  | 

RESINOUS    CEMENTS. 

Resinous  cement  for  amber  is  obtained  by  melting  mastic 
in  linseed  oil.  Volatile  copal  lacquer  can  also  be  advan- 
tageously used  for  the  purpose. 

Cement  for  turners.  Melt  1  Ib.  of  rosin  in  a  tin  can  over 
the  fire,  and  when  melted  add  4  ozs.  of  pitch  ;  while  these 
are  boiling  add  brick  dust  until,  by  dropping  a  little  on  a 
cold  stone,  you  think  it  is  hard  enough.  In  winter  it  may 
be  found  necessary  to  add  a  little  tallow. 

By  means  of  this  cement  a  piece  of  wood  may  be  fastened 
to  the  chuck,  which  will  hold  when  cool,  and  when  the 
work  is  finished,  it  may  be  removed  by  a  smart  blow  with 
the  tool.  All  traces  of  the  cement  may  be  removed  from 
the  work  by  repeated  applications  of  benzine.  To  use  this 
cement,  chip  off  as  much  as  will  cover  the  chuck  to  the 
-feth  of  an  inch,  spread  it  over  the  surface  in  small  pieces, 
mixing  it  with  J  of  its  bulk  of  gutta-percha,  then  heat  an 
iron  to  a  dull  red  heat,  and  hold  it  over  the  chuck  till  the 
mixture  and  gutta-percha  are  melted  and  liquid.  Stir  the 


230  GLUE,    GELATINE,    CEMENTS,    PASTES. 

cement  until  it  is  homogeneous,  chuck  the  work,  lay  on  a 
weight  to  enforce  contact,  leave  it  at  rest  20  minutes. 

The  following  cement  is  much  employed  and  serviceable 
for  the  use  of  turners  and  artisans  in  general. 

Reduce  1  Ib.  of  whiting  to  a  fine  powder,  and  heat  to 
redness  so  as  to  expel  all  the  water.  When  cold  this  is 
mixed  with  1  Ib.  of  black  rosin  and  1  oz.  of  beeswax  pre- 
viously melted  together,  and  the  whole  stirred  till  of  uni- 
form consistence. 

Cement  for  ivory  and  bone.  Melt  at  a  moderate  heat  equal 
parts  of  white  wax,  rosin,  and  oil  of  turpentine  to  form 
a  thickly-fluid  mass.  For  coloring  the  cement  add  elutri- 
ated red  lead,  ultramarine,  etc, 

Cement  for  white  enameled  clock-faces.  Dammar  resin  100 
parts,  copal  100,  Venice  turpentine  110,  zinc  white  60, 
ultramarine  3. 

Apply  hot  and  polish  when  cold  and  hard. 

Cements  for  glass.  1.  Melt  carefully  60  parts  of  bleached 
shellac  and  10  of  turpentine.  If  too  thick,  dilute  with 
turpentine. 

2.  Shellac  20  parts,  elemi  5,  turpentine  10.  Prepare  as 
above. 

Cement  for  glass  upon  glass.  Shellac  10  parts,  turpentine 
2,  pulverized  pumice  stone  10. 

Cement  for  glass  upon  metal.  Melt  together  40  parts  of 
rosin,  20  of  rouge,  10  of  wax,  and  10  of  turpentine.  Apply 
hot  to  the  surfaces  to  be  cemented. 

Cement  for  metal  letters  upon  glass.     Rosin  42  parts,  tur- 

7entine  4,  plaster  of  Paris  5. 
Cement  for  wood.     100  parts  of  shellac  and  45  of  strong 
spirit  of  wine. 

This  cement  serves  for  joining  wood,  which,  on  account 
of  exposure  to  water,  cannot  be  glued.  Apply  the  cement 
to  the  surface  of  one  of  the  pieces,  and  after  placing  upon 
it  a  piece  of  tissue  paper  press  upon  it  the  other  piece  of 
wood  previously  coated  with  the  cement,  r 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       231 

Cement  for  knife  handles.  Melt  together  20  parts  of  rosin, 
5  of  sulphur,  and  8  of  iron  filings. 

Pour  some  of  the  hot  mixture  into  the  handle,  and  then 
push  in  the  knife  previously  heated. 

Cement  for  petroleum  lamps.  Boil  12  parts  of  rosin  in  16 
of  strong  lye  until  it  is  entirely  dissolved  and  on  cooling 
forms  a  tenacious  solid  mass.  Dilute  this  with  20  parts  of 
water,  and  carefully  work  into  it  20  parts  of  plaster  of 
Paris.  This  cement  is  insoluble  in  petroleum,  and  is  espe- 
cially adapted  for  cementing  the  glass  parts  of  lamps  to  the 
metal.  It  is  also  a  good  material  for  stoppers  for  petroleum 
bottles. 

Cement  for  porcelain.  Rosin,  14  parts  ;  elemi,  7  ;  shellac, 
7  ;  mastic,  7  ;  sulphur,  42  ;  brick  dust,  20. 

Cement  for  porcelain  which  is  to  be  heated.  Heat  carefully 
10  parts  of  amber  in  a  large  spoon,  stirring  constantly,  until 
it  evolves  heavy  vapors  of  a  strong  odor.  Rub  the  melted 
mass  as  finely  as  possible,  and  after  placing  the  powder  in  a 
bottle  pour  over  it  a  mixture  of  bisulphide  of  carbon  and 
benzine.  Close  the  bottle  air-tight  to  prevent  the  evapora- 
tion of  the  very  volatile  solvent.  When  the  powder  is  dis- 
solved remove  the  cork  and  replace  it  by  one  provided  with 
a  small  brush.  The  application  of  the  cement  and  pressing 
together  of  the  parts  to  be  cemented  must  be  effected  as 
quickly  as  possible.  In  articles  properly  cemented  the 
joint  can  only  be  detected  by  the  closest  examination. 
This  cement  holds  so  well  that  cups  and  saucers,  soup- 
tureens,  etc.,  mended  with  it  can  be  used  for  years. 

Cement  to  withstand  the  action  of  petroleum.  Dissolve  5 
parts  of  shellac,  1  of  turpentine  in  15  of  petroleum.  This 
cement  is  quite  elastic. 

Cement  for  mica.  A  colored  cement  for  joining  sheets  of 
mica  is  prepared  as  follows :  Soak  clean  gelatine  in  water, 
and  when  swelled  squeeze  out  the  excess  of  water  by  pres- 
sure between  a  cloth,  then  melt  the  gelatine  by  the  heat  of 
a  water-bath,  and  stir  in  just  enough  proof  spirit  to  make  it 


232  GLUE,    GELATINE,    CEMENTS,    PASTES. 

fluid.  To  each  part  of  this  solution  add,  while  stirring,  J 
oz.  of  gum  ammoniac  and  1J  ozs.  of  gum  mastic  dissolved 
in  4  ozs.  of  rectified  alcohol.  Put  the  mixture  into  bottles, 
and  when  required  for  use  stand  the  bottle  in  hot  water. 
This  cement  resists  cold  water. 

Cement  for  horn,  whalebone  and  tortoise  shell.  Dissolve 
gum  mastic  10  parts  and  turpentine  4,  in  12  of  linseed  oil. 
Apply  hot. 

Cement  for  terra-cotta  articles.  Melt  together  70  parts  of 
rosin,  70  of  wax  and  16  of  sulphur,  and  stir  into  the  mass  8 
parts  of  hammer  slag  and  8  of  quartz  sand.  Coat  the  frac- 
tured surfaces  with  oil  of  turpentine,  apply  the  cement  as 
quickly  as  possible,  and  press  the  surfaces  together.  It  is 
advisable  to  heat  the  terra  cotta  previously  to  158°  or  176° 
F.  After  cementing  the  article,  smooth  the  joint  with  a 
heated  knife  and  dust  very  fine  terra-cotta  powder  through 
a  linen  bag  upon  the  soft  cement  in  order  to  give  it  exactly 
the  same  color  as  the  article  itself. 

Mastic  cement  for  glass.  Gum  mastic  15  parts,  bleached 
shellac  10,  turpentine  5. 

This  mass  sufficiently  diluted  with  hot  oil  of  turpentine 
furnishes  an  excellent  cement  for  fractured  glass  and  gems. 
Being  colorless,  the  joint  can  scarcely  be  detected,  provided 
the  cementing  has  been  skilfully  done. 

To  attach  gems  to  glass  of  the  same  color,  the  cement  is 
colored  with  aniline  colors  dissolved  in  spirit  of  wine,  care 
being  had  to  give  it  the  same  shade  as  the  gem  and  the 
glass. 

Stick  mastic  cement.  Melt  together,  at  as  low  a  temper- 
ature as  possible,  10  parts  of  mastic  and  one  of  turpentine, 
and  pour  the  mass  into  suitable  moulds. 

For  use,  heat  the  fractured  surfaces  of  the  article  strongly, 
so  that  the  cement  on  being  rubbed  over  them  melts,  then 
press  the  surfaces  together  and  continue  the  pressure  until 
the  cement  solidifies. 

Sulphur  cement  for  porcelain.     White  pitch  18  parts,  sul- 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       233 

phur  28,  bleached  shellac  4,  gum  mastic  8,  elemi  8,  glass 
meal  28.  Melt  all  together,  except  the  glass  meal  and  stir 
the  latter  into  the  melted  mass. 

Insoluble  cement  for  wooden  vessels.  Melt  together  60  parts 
of  rosin,  20  of  asphalt,  and  40  of  brick  dust.  Pour  the  hot 
.mixture  into  the  joints.  This  cement  resists  the  action  of 
lye,  quick  lime,  sulphuric  and  hydrochloric  acids. 

RUBBER    CEMENTS. 

These  cements  are  very  useful,  but  owing  to  the  inflam- 
mable nature  of  the  components,  great  care  should  be  taken 
to  guard  against  fire  while  preparing  them.  They  should 
never  be  made  near  a  naked  fire,  as  the  benzine,  carbon 
disulphide  or  chloroform  used  to  dissolve  the  rubber  is  very 
volatile,  and  the  vapor  given  off  permeates  the  air  until, 
coming  near  a  source  of  light,  the  whole  air  becomes  one 
vivid  sheet  of  flame.  Vessels  which  are  used  should  be 
closed,  and  if  possible  put  out  of  doors.  If  heat  is  required 
to  assist  the  solvent  action,  use  a  sand  or  hot-water  bath, 
but  on  no  account  bring  near  a  fire. 

Cements  for  glass.  I.  Rubber  1  part,  gum  mastic  12, 
dammar  4,  chloroform  50,  benzine  10. 

II.  Rubber  12  parts,  chloroform  500,  gum  mastic  120. 
This  cement  adheres  immediately,  and  possesses  a  high 

degree  of  elasticity.  It  may  be  used  to  advantage  for  join- 
ing together  the  glass  panes  of  hot-houses. 

III.  Dissolve,  without  application  pf  heat,  rubber  2  parts 
and  gum  mastic  6,  in  100  of  chloroform.     This  cement  is 
perfectly  transparent.     It  should  be  applied  as  quickly  as 
possible,  as  it  sets  in  a  very  short  time. 

\(  Soft  rubber  cement.  Melt  10  parts  of  tallow  in  a  brass  pan 
and  gradually  add  150  parts  of  rubber  in  small  pieces,  and 
stir  constantly  until  all  the  rubber  is  dissolved.  Keep  in 
readiness  a  well-fitting  lid  to  be  able  to  extinguish  the 
flame  immediately  in  case  the  rubber  catches  fire.  When 
all  is  melted  stir  in  10  parts  of  slaked 


234  GLUE,    GELATINE,    CEMENTS,    PASTES. 

This  cement  is  especially  adapted  for  sealing  bottles  con- 
taining caustic  substances,  such  as  nitric  acid,  etc.  It  re- 
mains always  tenacious,  being  therefore  suitable  for  cement- 
ing bodies  exposed  to  repeated  shocks. 

Hard  rubber  cement.  Rubber,  150  parts  ;  tallow,  10  ;  red 
lead,  10. 

This  cement  is  prepared  in  the  same  manner  as  the  above. 
The  addition  of  red  lead  gives  it  a  red  color,  and  solidifies 
it  in  a  short  time  to  a  mass  as  hard  as  stone. 

Elastic  cement.  Carbon  disulphide,  8  ozs.  ;  fine  rubber, 
1  oz. ;  isinglass,  4  drachms ;  gutta-percha,  1  oz.  Dissolve 
the  solids  in  the  fluid. 

This  cement  is  used  for  cementing  leather  and  rubber. 
For  use  the  leather  is  roughened  and  a  thin  coat  of  the 
cement  applied  and  allowed  to  dry  completely  ;  then  the 
two  surfaces  to  be  joined  are  warmed  and  placed  together 
and  allowed  to  dry. 

Marine  glue.  This  cement,  which  is  only  a  glue  in  name, 
is  water-proof,  and  can  be  used  to  cement  metal,  wood,  glass, 
stone,  pasteboard,  etc.,  and  is  especially  adapted  for  caulk- 
ing vessels. 

Suspend  10  parts  of  rubber  inclosed  in  a  bag  in  a  vessel 
containing  120  parts  of  refined  petroleum,  so  that  only  half 
of  the  bag  is  immersed,  and  allow  it  to  remain  ten  to  four- 
teen days  in  a  warm  place.  Then  melt  20  parts  of  asphalt 
in  an  iron  boiler  and  add  the  rubber  solution  in  a  thin  jet, 
and  heat  the  mixture,  while  constantly  stirring,  until  it  is 
perfectly  homogeneous.  Pour  it  into  greased  metallic 
moulds,  where  it  forms  into  dark-brown  or  black  plates 
difficult  to  break.  In  using  it,  it  should  be  melted  in  a 
kettle  placed  in  boiling  water  to  prevent  its  burning,  which 
it  is  very  apt  to  do,  as  it  is  a  bad  conductor  of  heat.  After 
it  has  been  liquefied  remove  the  kettle  from  the  water  and 
place  it  over  a  fire,  where  it  can  be  heated,  if  necessary,  to 
make  it  more  fluid,  to  302°  F.,  carefully  stirring  it  to  pre- 
vent burning. 


PREPARATION  OP  CEMENTS,  PASTES,  AND  MUCILAGES.       235 

If  possible,  the  surfaces  to  be  glued  together  should  be 
heated  to  212°  F.,  as  the  glue  can  then  be  slowly  applied. 
The  thinner  the  layer  of  glue  in  cementing  together  smooth 
surfaces,  the  better  will  it  adhere.  But  a  somewhat  thicker 
layer  is  required  for  rough  surfaces,  for  instance,  boards  not 
planed,  the  excess  of  glue  being  forced  out  by  strong  pres- 
sure. Generally  speaking,  it  is  best  to  subject  all  articles 
cemented  together  with  marine  glue  to  as  strong  a  pressure 
as  possible  until  the  glue  is  congealed. 

Repeated  experiments  have  shown  that  with  the  aid  of 
this  cement  square  vats  perfectly  water-tight  can  be  con- 
structed of  boards.  Wooden  pegs  dipped  in  the  compound 
should  be  used  for  putting  the  vats  together. 

Jeffrey's  marine  glue.  Dissolve  1  part  of  rubber  in  ben- 
zine, and  mix  the  solution  with  2  parts  of  shellac  by  the 
assistance  of  heat. 

Another  formula  is  as  follows :  Coal  naphtha  1  quart, 
rubber  cut  in  shreds  2  ozs.  Macerate  for  10  or  12  days  and 
then  rub  smooth  with  a  spatula  on  a  slab  ;  add  2  parts  by 
weight  of  shellac  to  1  part  of  this  solution.  To  use  the 
compound  melt  it  at  about  240°  F. 

Marine  glue  for  damp  walls.  Rubber  10  parts,  whiting 
10,  oil  of  turpentine  20,  carbon  disulphide  10,  rosin  5  and 
asphalt  5.  Dissolve  the  ingredients  in  a  suitable  vessel  and 
stand  in  a  warm  place,  shaking  it  frequently. 

Scrape  the  wall  smooth  and  clean,  and  apply  the  glue 
with  a  broad  brush  on  the  damp  place  and  about  8  inches 
higher  than  the  line  of  dampness.  Before  the  glue  is  dry 
lay  on  plain  paper  whioh  will  adhere  tightly.  On  this 
plain  paper  the  wall  paper  can  be  pasted  in  the  usual  man- 
ner. If  carefully  done,  the  wall  paper  will  always  remain 
dry. 

GUTTA-PERCHA    CEMENTS. 

Cement  for  leather.  Gutta-percha  100  parts,  pitch  or 
asphalt  100,  oil  of  turpentine  15. 

This  cement   should    be   used    hot.     It   is   suitable    for 


236  GLUE,    GELATINE,    CEMENTS,    PASTES. 

cementing  all  kinds  of  substances,  but  adheres  particularly 
well  to  leather. 

Cement  for  hard  rubber  combs.  A.  Prepare  a  very  thick 
solution  of  bleached  gutta-percha  in  bisulphide  of  carbon. 

B.  Dissolve  sulphur  in  bisulphide  of  carbon. 

The  cementing  is  effected  by  applying  solution  A  to  the 
fractured  surfaces  and  pressing  them  together.  When  dry 
brush  solution  B  over  the  cemented  place. 

Elastic  gutta-percha  cement.  Dissolve  10  parts  of  gutta- 
percha  in  100  of  benzine,  then  pour  the  clear  solution  into 
a  bottle  containing  100  parts  of  linseed-oil  varnish  and 
unite  both  by  shaking.  This  cement  excels  in  elasticity, 
and  is  especially  suitable  for  attaching  the  soles  of  shoes,  as 
it  is  so  elastic  that  it  will  not  break,  no  matter  how  much  it 
is  bent.  To  make  it  adhere  tightly  roughen  the  leather  on 
the  side  to  be  cemented. 

Cement  for  horses'  hoofs.  For  filling  cracks  and  fissures 
in  horses'  hoofs  a  cement  is  required  which  possesses  great 
resistance  to  the  action  of  water  combined  with  elasticity 
and  solidity.  A  mass  answering  all  demands  consists  of  10 
parts  by  weight  of  gum  ammoniac  and  20  to  25  of  purified 
gutta-percha.  Heat  the  gutta-percha  to  between  194°  and 
212°  F.,  and  then  work  it  with  the  finely  powdered  gum 
ammoniac  to  a  homogeneous  mass.  In  using  it,  soften  the 
cement  by  heating,  and  after  carefully  cleansing  the  crack 
in  the  hoof,  apply  it  with  a  heated  knife.  The  cement 
solidifies  immediately  after  cooling  to  the  ordinary  tem- 
perature, and  becomes  soon  so  hard  as  to  allow  of  nails  be- 
ing driven  into  it. 

Cement  for  crockery.     Gutta-percha  1  part,  shellac  1. 

Place  the  two  ingredients  in  an  earthenware  jar,  and 
melt  the  two  together  by  standing  this  jar  on  a  vessel  of 
boiling  water,  or  else  one  filled  with  hot  sand,  the  vessel 
holding  the  water  or  sand  being  heated  over  a  fire  or  gas 
furnace.  Stir  the  melted  ingredients  well  together.  The 
resulting  cement  is  one  possessing  great  hardness  and 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       237 

toughness,  which  suits  it  admirably  for  mending  crockery. 
Warm  the  edges  to  be  joined  together,  smear  the  cement  on, 
join  together,  and  hold  the  article  thus  joined  until  cool. 

Cem.ent  for  leather.  Mix  10  parts  of  carbon  disulphide 
with  1  part  of  turpentine,  and  then  add  sufficient  gutta 
percha  to  make  a  tough,  thickly-fluid  mass.  Before  using 
this  cement,  free  the  surface  to  be  joined  from  grease.  To 
effect  this,  sprinkle  a  little  bicarbonate  of  soda,  carbonate  of 
ammonia  or  borax  on  the  surfaces  to  be  joined,  lay  a  cloth 
over  them,  and  then  place  a  hot  iron  on  top,  and  keep  it 
there  a  short  time  so  as  to  cause  the  alkali  to  cut  the  grease, 
then  put  the  cement  on  both  surfaces  to  be  joined,  put  them 
together  and  subject  to  pressure  until  they  are  cemented. 

Gutta  percha  dissolved  in  carbon  disulphide  to  the  con- 
sistency of  syrup  is  also  a  good  cement  for  joining  leather. 
The  parts  to  be  joined  should  be  well  covered  with  cement 
so  as  to  fill  the  pores  of  the  leather,  then  the  cement  is 
heated  and  the  parts  hammered  until  the  cement  is  cold. 

CASEINE    CEMENTS. 

Preparation  of  pure  caseine.  Although  the  caseine  con- 
tained in  old  cheese  can  be  used,  the  other  constituents, 
such  as  fat,  salt,  and  free  acid,  exert  an  injurious  influence 
upon  the  solidity  of  the  cement  prepared  with  it.  It  is, 
therefore,  best  to  prepare  pure  caseine,  which  is  easily 
accomplished  in  the  following  manner : 

Put  milk  in  a  cool  place,  and  after  taking  off  the  cream 
as  long  as  any  is  formed,  remove  the  skimmed  milk  to  a 
warm  place  to  coagulate.  After  heating  the  curd,  place  it 
upon  a  filter  and  wash  the  caseine  remaining  upon  the 
filter  with  rainwater  until  the  water  running  off  shows  no 
trace  of  acid. 

To  remove  the  last  traces  of  fat  tie  the  washed  caseine  in 
a  cloth  and  after  boiling  it  in  water,  spread  it  upon  blotting 
paper  in  a  warm  place  to  dry.  It  will  shrivel  up  to  a 
horny  mass. 


238  GLUE,    GELATINE,    CEMENTS,    PASTES. 

When  thoroughly  dried  pure  caseine  will  keep  for  a  long 
time  without  suffering  alteration.  To  obtain^the  caseine  in 
a  form  suitable  for  preparing  cements  it  is  only  necessary 
to  pour  water  over  a  corresponding -quantity  and  allow  it 
to  stand  for  some  time.  Caseine  combines  with  lime  to  a 
hard  insoluble  mass. 

Ordinary  technical  caseine  may  be  readily  and  cheaply 
prepared  as  follows  :  Skim  milk  is  heated  in  a  copper  boiler, 
if  necessary  by  the  introduction  of  steam,  to  122°  F.  Then 
add  for  every  1000  quarts  of  milk,  3  quarts  of  crude  hydro- 
chloric acid  diluted  with  5  to  6  times  the  quantity  of  water. 
After  coagulation,  the  whey  is  drained  off,  the  curd  spread 
out  upon  an  inclined  table  and  allowed  to  cool.  The  curd 
is  then  washed  by  pouring  cold  water  over  it  through  a 
rose,  or  stirring  it  up  with  water  in  a  barrel,  allowing  to 
settle,  and  pouring  off  the  supernatant  water.  The  residue 
is  subjected  to  moderate  pressure.  The  caseine  while  still 
moist  is  comminuted  in  a  curd-mill  and  packed  in  bags. 
In  this  state  it  must  be  worked  at  once,  as  otherwise  it 
spoils  readily  and  is  attacked  by  worms.  If  it  is  to  be  kept 
for  a  longer  time,  it  has  to  be  dried.  This  is  effected  by 
spreading  it  out  upon  linen  cloths  and  placing  it  in  a  dry- 
ing chamber. 

In  this  manner  8.5  per  cent,  of  moist,  or  3.5  per  cent,  of 
dry,  caseine  is  obtained  which  is  brought  into  commerce  as 
technical  caseine  or  lactarine.  It  being  insoluble  in  water, 
10  per  cent,  of  an  alkali — soda,  borax,  or  ammonia — has  to 
be  added  to  effect  solution.  Water-soluble  caseine  is  seldom 
found  in  commerce,  the  consumer  preparing  it,  as  a  rule, 
himself. 

A  purer  technical  caseine  is  obtained  according  to  John 
A.  Just's  method  as  follows  :  Dissolve,  stirring  constantly, 
in' 115  quarts  of  water  heated  to  between  104*  and  131°  F., 
17  to  26  ozs.  of  bicarbonate  of  soda  and  176  Ibs.  of  moist,  or 
118  Ibs.  of  dry,  caseine,  and  dry  the  solution  upon  a  heated 
revolving  metal  cylinder.  After  each  revolution  of  the 


PREPARATION  OP  CEMENTS,  PASTES,  AND  MUCILAGES.       239 

cylinder,  the  dry  material  is  scraped  off  with  brushes  and 
by  being  forced  through  a  fine-meshed  sieve  yields  soluble 
caseine  powder. 

Caseine  cement  which  can  be  kept  for  a  long  time.  Convert 
into  powder,  each  by  itself,  200  parts  of  caseine,  40  of 
burned  lime,  and  1  of  camphor.  Mix  the  powders  inti- 
mately and  keep  the  mixture  in  an  air-tight  bottle.  For 
use,  mix  some  of  the  powder  with  the  requisite  quantity 
of  water  and  use  the  cement  at  once. 

/  Cement  for  glass.  Old  dry  cheese  100  parts,  water  50, 
slaked  lime  20. 

Free  the  cheese  from  rind,  and  rub  it  with  the  water 
until  a  homogeneous  mass  drawing  threads  is  formed. 
Then  stir  in  quickly  the  lime  powder,  and  use  the  cement 
at  once.  It  unites  not  only  glass  to  glass,  but  can  also  be 
used  for  cementing  metal  to  glass. 

Cement  for  metals.  Elutriated  quartz  sand,  10  parts; 
caseine,  8  ;  slaked  lime,  10,  and  sufficient  water  to  form  a 
cream-like  mass.j' 

Cement  for  porcelain.  Caseine  dissolves  readily  in  solu- 
tion of  water-glass,  and  forms  then  one  of  the  best  cements 
for  porcelain  known.  To  prepare  it,  fill  a  bottle  one- 
quarter  full  with  fresh  caseine,  and  after  filling  the  bottle 
with  solution  of  water-glass,  effect  the  solution  of  the  caseine 
by  frequent  shaking. 

Cement  for  meerschaum.  Dissolve  caseine  in  water-glass, 
and  after  stirring  quickly  finely-pulverized  calcined  mag- 
nesia into  the  mass,  use  it  at  once,  as  it  solidifies  very  soon. 
By  adding,  besides  magnesia,  genuine  meerschaum  finely 
pulverized,  a  mass  closely  resembling  meerschaum  is  ob- 
tained, which  can  be  used  for  manufacturing  imitation 
meerschaum. 

/y  Cement  for  wood,  etc.  Rub  10  parts  of  caseine  and  5  of 
borax  to  a  thick,  milky  mass,  and  use  it  like  glue.  This 
cement  can  be  advantageously  used  for  pasting  labels  upon 
wine  bottles,  as  it  neither  moulds  nor  becomes  detached  in 
the  cellar,  t 


240  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Another  formula  is  as  follows:  Dissolve  borax  by  boiling 
in  water,  and  pour  the  solution  over  fresh  caseine.  The 
result  will  be  a  clear,  thick  mass  of  extraordinary  power  of 
adhesion,  which  can  be  kept  for  any  length  of  time  without 
suffering  decomposition,  j 

Applied  to  leather,  paper,  linen  or  cotton  goods,  it  forms 
a  coat  of  beautiful  lustre,  and  for  this  reason  is  much  used 
in  the  manufacture  of  fancy  articles  of  paper  and  leather. 

Cement  for  porcelain.  Dissolve  10  parts  of  caseine  in  60 
of  water-glass  solution.  Apply  the  cement  quickly  and  dry 
the  cemented  articles  in  the  air. 

WATER-GLASS    AND    WATER-GLASS    CEMENTS. 

Water-glass.  Water-glass  (silicate  of  soda  or  soluble 
glass)  is  found  in  commerce  as  a  thickly-fluid,  tenacious 
mass.  It  is  generally  prepared  by  fusing  15  parts  of  quartz 
sand  with  8  of  carbonate  of  soda  and  1  of  charcoal.  The 
silicic  acid  combining  with  the  soda  disengages  the  car- 
bonic acid,  the  expulsion  of  which  is  facilitated  by  the  pre- 
sence of  charcoal,  which  converts  it  into  carbonic  oxide.  It 
dissolves  readily  in  water.  The  solution  has  a  strongly 
alkaline  taste,  and  possesses  the  property  of  being  gradually 
converted,  on  exposure  to  the  air,  to  a  gelatinous  mass 
which  finally  solidifies.  For  this  reason  water-glass  should 
be  kept  in  bottles  hermetically  closed  with  corks.  Glass 
stoppers  are  of  no  use,  as  they  are  so  firmly  cemented  to  the 
bottle  that  on  attempting  to  open  the  latter  the  neck  breaks 
off. 

By  combining  water-glass  with  cement  or  burned  lime 
the  resulting  mass  solidifies  quite  rapidly  to  a  mass  as  hard 
as  stone,  and  generally  capable  of  resisting  chemical  action. 

Water-glass  by  itself  is  only  fit  for  cementing  glass  to 
glass,  but  combined  with  other  substances  it  furnishes  very 
durable  and  solid  cements.  • 

Cement  for  cracked  bottles.  Select  a  cork  which  will  fit  the 
bottle  air-tight  and  place  it  loosely  upon  the  bottle,  and  heat 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       241 

the  latter  gradually  to  at  least  212°  F.  Then  press  the 
cork  down  and  apply  a  thick  solution  of  water-glass  to  the 
cracks.  In  cooling,  the  air  in  the  bottle  contracts  strongly, 
and  the  pressure  of  the  exterior  air  drives  the  water-glass 
with  great  force  into  the  cracks  closing  them  entirely  so 
that  they  cannot  be  detected. 

Cement  for  glass  and  porcelain.  Stir  quickly  together  10 
parts  of  elutriated  glass  meal,  20  of  powdered  fluor  spar, 
and  60  of  water-glass  solution,  and  apply  the  homogeneous 
paste  at  once.  In  a  few  days  the  cement  will  be  so  hard 
that  the  cemented  vessels  can  be  heated  without  danger. 

Cement  for  hydraulic  works.  Finely  powdered  cement,  and 
solution  of  water-glass.  Mix  the  two  bodies  quickly  together. 

As  this  cement  hardens  very  quickly,  it  should  be  used 
fresh.  It  hardens  under  water,  and  is  therefore  excellent 
for  hydraulic  works.  The  stones  should  be  coated  with 
a  solution  of  water-glass  before  applying  the  cement. 

Cement  for  uniting  metals.  A  strong  cement,  which 
hardens  rapidly,  is  made  by  stirring  the  finest  whiting  in  a 
solution  of  soda-glass  of  33°  B.,  made  so  as  to  form  a  plastic 
mass.  This  can  be  readily  colored  to  any  desired  shade. 
The  addition  of  sifted  sulphide  of  antimony  gives  a  black 
cement,  which  by  polishing  acquires  a  metallic  lustre ;  iron 
filings  render  it  grayish-black  ;  zinc  dust  turns  it  green,  but 
after  polishing,  it  appears  like  metallic  zinc,  and  may  be 
employed  for  the  permanent  repair  of  zinc  ornaments,  etc. 
Carbonate  of  copper  imparts  a  light  green  shade.  Other 
additions  may  be  made,  as  oxide  of  chrome  for  dark  green, 
cobalt  blue  for  blue,  red  lead  for  orange,  vermilion  for 
scarlet,  carmine  for  violet,  etc.J 

Cement  for  tightening  joints  of  pipes  exposed  to  a  red  heat. 
Mix  80  parts  of  pyrolusite,  100  of  zinc  white,  and  20  of 
water-glass. 

This  cement  fuses  at  a  temperature  not  too  high,  and 
then  forms  a  glass-like  mass  which  adheres  very  firmly  and 
closely. 

16 


242  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Cement  for  marble  and  alabaster.  The  point  of  fracture  of 
articles  cemented  with  the  following  mixture  is  difficult  to 
find,  and  the  cemented  place  is  much  stronger  than  the 
material  itself.  Mix  12  parts  of  Portland  cement,  6  of 
slaked  lime,  6  of  fine  sand,  and  1  of  infusorial  earth  with 
sufficient  water-glass  to  form  a  thick  paste.  The  article  to 
be  cemented  need  not  be  heated.  It  hardens  in  twenty  - 
,four  hours. 

GLYCERINE  AND  GLYCERINE  CEMENTS. 

Commercial  glycerine  is  a  yellowish  or  nearly  colorless 
and  more  or  less  viscid  liquid  having  an  intensely  sweet 
taste.  In  combination  with  lead  oxide  and  intimately 
worked  into  it,  by  heating  and  stamping,  it  furnishes  very 
strong  and  durable  cements  deserving  general  introduction, 
though  thus  far  they  have  been  but  little  used.  | 

For  the  manufacture  of  cements  the  use  of  pure  odorless 
glycerine  is  not  required,  the  yellow  crude  article,  which  is 
much  cheaper,  answering  all  purposes.  The  principal 
point  is  to  use  very  highly  concentrated  glycerine,  as  other- 
wise the  cements  prepared  with  it  solidify  very  slowly  and 
besides  do  not  possess  a  proper  degree  of  hardness  and 
solidity. 

It  is  of  especial  importance  to  have  the  lead  oxide  free 
from  water.  To  accomplish  this,  heat  it  thoroughly  and 
mix  it  with  the  glycerine  while  still  hot.  Cement  thus 
prepared  solidifies  very  quickly,  and  can  be  used  for  many 
purposes.  It  is  an  excellent  material  for  quickly  joining 
the  stories  of  submarine  works. 

Glycerine  and  litharge  cement.  Moisten  elutriated  lith- 
arge with  glycerine  so  that  a  thin  homogeneous  paste  is 
formed.  This  cement  is  adapted  for  uniting  the  joints  of 
steam  pipes,  cementing  wood,  glass,  porcelain,  and  also 
glass  upon  metal,  etc.  It  solidifies  to  a  very  hard  mass  in 
a  quarter  to  three-quarters  of  an  hour.  Before  applying 
the  cement  coat  the  surfaces  to  be  joined  with  pure 
glycerine,  f 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       243 
LIME  CEMENTS. 

Quick  lime,  slaked  lime  and  chalk  are  used  for  this  pur- 
pose. Quick  lime,  which  is  obtained  by  burning  limestone, 
combines  gradually  with  the  fats  to  insoluble  lime  soaps. 
Slaked  lime,  which  consists  of  a  combination  of  lime  with 
water,  acts  in  the  same  manner. 

For  the  preparation  of  cements  the  lime  is  slaked  by 
placing  it  in  a  dish  and  pouring  as  much  water  over  it  as 
it  will  absorb.  Good  lime,  technically  called  fat  lime, 
should  eagerly  combine  with  water,  evolving  much  heat, 
swelling  greatly,  and  crumbling  to  a  light  white  powder. 

Quick  lime  exposed  to  the  air  until,  by  the  absorption  of 
moisture  and  carbonic  acid,  it  is  converted  into  a  powder  is 
called  air-slaked. 

Cements  prepared  with  quick  lime  will,  as  a  rule,  solidify 
more  quickly  than  those  prepared  with  air-slaked  lime. 

Chalk  is  a  carbonate  of  lime  consisting  of  the  shells  of 
microscopic  animals,  and  can  be  readily  pulverized  and 
elutriated.  In  the  latter  state  it  is  known  as  whiting.  For 
the  preparation  of  entirely  white  cements  the  use  of  pure 
white  lime  or  chalk  is  absolutely  necessary.  Yellow  or 
reddish  lime  contains  oxide  of  iron,  and  furnishes  cements 
of  the  same  tinge. 

Cement  for  glass.  Litharge  30  parts,  quick  lime  20,  lin- 
seed-oil varnish  5. 

Cement  for  joiners.  A  cement  for  filling  up  cracks  and 
holes  is  obtained  by  mixing  slaked  lime  50  parts,  flour  100, 
linseed-oil  varnish  15. 

Cement  for  cracked  clay  crucibles  and  porcelain.  By  apply- 
ing to  the  cracks  a  mixture  of  10  parts  of  slaked  lirne,  10 
of  borax,  and  5  of  litharge  in  sufficient  water  to  form  a  stiff 
paste,  and  drying  after  heating  the  crucible,  the  cracked 
places  will  be  united  so  firmly  that  the  crucible,  when 
thrown  to  the  ground,  will  generally  break  in  any  other 
place  than  the  cemented  one. 


244  GLUE,    GELATINE,    CEMENTS,    PASTES. 

This  cement  can  also  be  used  for  porcelain  capable  of 
standing  a  strong  heat. 

Lime  and  glue  cement.  Stir  air-slaked  lime  into  hot  glue. 
This  cement  is  especially  suitable  for  attaching  metal  to 
glass.  It  forms  a  very  hard  yellowish-brown  mass. 

GYPSUM    CEMENTS. 

Sulphate  of  lime  in  combination  with  water  is  met  with 
in  nature,  both  in  the  form  of  transparent  prisms  of  selenite, 
and  in  opaque  and  semi-opaque  masses,  known  as  alabaster 
and  gypsum.  By  pulverizing  the  latter  and  heating  to 
about  302°  F.  it  loses  its  water,  and  is  converted  into 
anhydrous  gypsum  or  plaster  of  Paris,  which  on  mixing 
with  water  recom bines  with  it  to  form  a  mass  of  hydrated 
sulphate  of  lime,  the  hardness  of  which  nearly  equals  that 
of  the  original  gypsum.  When  the  powder  is  mixed  with 
water  to  a  cream  and  poured  into  a  mould,  the  minute  par- 
ticles of  anhydrous  sulphate  of  lime  combine  with  the 
water  to  reproduce  the  original  gypsum,  and  this  act  of 
combination  is  attended  with  a  slight  expansion  which 
forces  the  plaster  into  the  finest  lines  of  the  mould. 

By  using  a  solution  of  alum  instead  of  ordinary  water,  a 
plaster  is  obtained  which,  although  it  takes  much  longer  to 
set  than  the  ordinary  kind,  is  much  harder,  and  therefore 
takes  a  good  polish. 

For  preparing  cements  only  perfectly  white  plaster  of 
Paris  should  be  used,  as  the  gray  article  possesses  but  little 
adhesive  power. 

Cement  for  plaster  of  Paris  statues.  To  repair  plaster  of 
Paris  statues  so  that  the  point  of  fracture  cannot  be  detected, 
proceed  in  the  following  manner : 

Moisten  the  fractured  surfaces  with  water  by  means  of  a 
brush  until  they  absorb  no  more  and  remain  moist.  Mix 
plaster  of  Paris  with  water  to  a  thin  cream  and  stir  until 
the  heat  appearing  at  first  has  ceased,  which  will  prevent 
the  conversion  of  the  plaster  into  a  solid  coherent  mass. 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       245 

Apply  quickly  a  thin  layer  of  the  plaster  to  one  of  the  frac- 
tured surfaces,  press  the  other  against  it  until  the  plaster 
has  set,  and,  when  dry,  carefully  remove  the  excess  by 
scraping. 

Cement  for  glass  and  porcelain.  Mix  quickly  50  parts  of 
plaster  of  Paris,  10  of  quick  lime,  and  20  of  white  of  egg. 
Use  at  once,  as  the  cement  solidifies  very  rapidly. 

Cement  for  iron  and  stone.  A  very  useful  cement  for 
securing  iron  railing  in  stone  is  obtained  by  mixing  30 
parts  of  plaster  of  Paris,  10  of  iron  filings  and  20  of  vinegar. 

Cements  for  porcelain.  I.  Mix  plaster  of  Paris  with  satu- 
rated solution  of  alum  to  a  cream.  After  moistening  the 
fractured  surfaces  apply  a  thin  layer  of  the  cement,  press 
the  surfaces  together,  wrap  a  wire  or  cord  tightly  around 
them,  and  let  the  article  stand  quietly  for  a  few  weeks. 
The  cement  is  converted  into  a  mass  as  hard  as  stone. 

II.  Mix  plaster  of  Paris  with  a  thick,  clear  solution  of 
gum  arabic  and  cement  the  articles  as  soon  as  possible. 
Although  this  cement  adheres  very  tightly,  porcelain  ves- 
sels cemented  with  it  cannot  be  used  for  liquids. 

Universal  plaster  of  Paris  cement.  Mix  21  parts  of 'plaster 
of  Paris,  3  of  iron  filings,  10  of  water,  and  4  of  white  of 
egg.  This  cement  is  suitable  for  attaching  metal  to  glass, 
metal  to  stone,  etc. 


IRON    CEMENTS. 

Heat-resisting  cement.  Clay  10  parts,  iron  filings  5,  vine- 
gar 2,  water  3. 

Water  and  steam-proof  cement.  Iron  filings  100  parts,  sal- 
ammoniac  2,  water  10. 

This  cement  rusts  very  much  in  a  few  days,  and  is  con- 
verted into  an  extremely  solid  mass  which  is  perfectly 
steam-  and  water-proof. 

Cement  for  iron.  Mix  65  parts  of  wrought-iron  filings, 
2.5  of  sal  ammoniac,  and  ]  .5  of  flowers  of  sulphur,  and  then 
add  1  part  of  sulphuric  acid  diluted  with  sufficient  water  to 


246  GLUE,    GELATINE,    CEMENTS,    PASTES. 

form  a  stiff  paste.  This  cement  solidifies  in  two  to  three 
days,  and  rusts,  with  the  parts  of  iron  to  be  cemented,  to  an 
extraordinarily  durable  mass./ 

Fire-proof  cement  for  iron  pipes.  Wrought-iron  filings  45 
parts,  clay  20,  fire-clay  15,  common  salt  solution  8. 

Cements  resisting  high  temperatures.  1.  Iron  filings  20 
parts,  clay  powder  45,  borax  5,  common  salt  5,  pyrolu- 
site  10. 

Dissolve  the  borax  and  common  salt  in  the  water,  add 
and  mix  quickly  the  clay  powder,  pyrolusite,  and  iron 
filings.  Apply  the  cement  at  once.  Exposed  to  a  white 
heat,  it  hardens  to  a  tightly  adhering,  glassy  mass. 

2.  Mix  52  parts  of  pyrolusite,  25  of  zinc  white,  and  5  of 
borax' with  solution  of  water-glass  to  a  paste,  and  use  at 
once.  This  cement  requires  to  be  gradually  dried.  It  will 
stand  the  highest  temperatures. 

Cement  for  filling  in  defects  in  castings.  Stir  100  parts  of 
iron  filings  free  from  rust  with  sufficient  water  to  form  a 
thick  paste,  and  press  the  mixture  into  the  fissures,  cracks, 
etc.  The  cement  becomes  solid  only  after  the  iron  filings 
become  strongly  rusted.  To  free  the  ingredients  from 
adhering  fat,  wash  them,  before  mixing,  in  liquid  ammonia. 

Cement  for  cracked  stove  plates,  etc.  Knead  20  parts  of  iron 
filings,  12  of  iron  scale,  30  of  plaster  of  Paris,  and  10  of 
common  salt  with  blood  to  a  stiff  paste,  and  use  at  once. 
Instead  of  blood,  water-glass  can  be  used,  it  having  the  ad- 
vantage of  being  odorless  on  strong  heating,  while  blood 
cement  evolves  a  disagreeable  odor. 

Cement  for  iron  water  tanks.  Knead  iron  filings  with 
vinegar  to  paste.  Allow  the  mixture  to  stand  until  it  turns 
brown,  and  then  force  it  into  the  joints  by  means  of  a 
chisel. 

Cement  for  cracked  iron  pots.  Knead  10  parts  of  iron 
filings  and  60  of  clay  with  linseed  oil  to  a  thick  paste. 
Before  applying  it  add  a  little  linseed  oil,  and  allow  it  to 
dry  slowly.  In  a  few  weeks  the  cement  will  be  so  hard 
that  the  vessels  can  be  used  without  danger. 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       247 

Black  cement  for  stoves.  Iron  filings  10  parts,  sand  12, 
bone  black  10,  slaked  lime  12,  glue  water  5. 

Cements  for  iron  stoves.  1.  Pulverize  as  finely  as  possible 
and  mix  intimately  4  to  5  parts  of  clay,  2  of  iron  filings 
free  from  rust,  1  of  pyrolusite,  J  of  common  salt,  and  J  of 
-borax  with  water  to  a  paste,  and  apply  the  cement  quickly 
to  the  places  to  be  cemented  and  allow  it  to  dry  slowly. 
This  cement  will  stand  a  white  heat,  and  resist  the  action 
of  boiling  water. 

2.  Mix  intimately  and  as  quickly  as  possible  1  part  of 
pulverized  pyrolusite,  and  1  of  zinc  white  with  solution  of 
water-glass  to  a  plastic  mass,  which  solidifies  quickly.  The 
power  of  resistance  of  this  cement,  it  is  claimed,  is  not  in- 
ferior to  No.  1,  though  experiments  have  proved  No.  1  to 
be  preferable. 

CEMENTS    FOR    CHEMICAL    APPARATUS. 

Cements  to  be  used  for  the  above  purpose  must  possess 
various  properties  difficult  to  combine  in  one  preparation. 
They  must  be  gas-proof,  and  capable  of  resisting  the  action 
of  different  vapors  and  acid  fluids.  As  regards  resistance 
to  the  action  of  chemical  agents,  there  is  nothing  better 
than  caoutchouc,  but  unfortunately  it  can  only  be  used  for 
tightening  chemical  apparatus  not  exposed  to  a  high  tem- 
perature. 

In  chemical  laboratories  bran  of  almonds,  either  by  itself 
or  kneaded  with  water  to  a  thick  paste,  is  frequently  used, 
or  rye  or  wheat  bran  mixed  with  a  little  flour  and  water. 
These  cements,  though  very  suitable  for  cementing  glass 
distilling  apparatus,  are  strongly  acted  upon  by  chlorine 
and  the  vapors  of  nitric  acid. 

For  small  apparatus  to  be  used  for  the  development  of 
fluoric  acid,  plaster  of  Paris  mixed  with  a  little  water  can 
be  used  as  a  cement.  To  make  the  joint  entirely  gas-tight, 
paste  a  strip  of  paper  over  it.  Although  this  cement  does 
not  resist  the  action  of  fluoric  acid  for  any  length  of  time,  it 


248  GLUE,    GELATINE,    CEMENTS,    PASTES. 

suffices  generally  for  the  protection  of  the  Workmen  during 
the  time  the  development  of  the  acid  is  in  progress,  as,  for 
instance,  in  chemical  analyses,  etc. 

To  cement  chemical  apparatus  exposed  to  a  temperature 
not  exceeding  86°  to  104°  F.  paraffine  does  excellent  ser- 
vice ;  as  it  possesses  the  power  of  resisting  the  action  of  the 
strongest  acids  and  alkalies. 

Below  will  be  found  a  few  receipts  for  cements  which 
have  proved  reliable. 

Linseed  oil  and  clay  cement.  Knead  10  parts  of  dry  clay 
with  1  of  linseed  oil  to  a  homogeneous  mass.  This  cement 
will  stand  heating  to  the  boiling-point  of  mercury. 

Linseed  oil,  zinc  and  manganese  cement.  Knead  10  parts 
of  pyrolusite,  20  of  zinc  white,  and  40  of  clay  with  suffi- 
cient boiled  linseed  oil  (not  exceeding  7  parts)  to  a  plastic 
mass.  This  cement  will  stand  a  somewhat  higher  tempera- 
ture than  the  preceding  one. 

Cements  resisting  very  high  temperatures.  I.  Clay  100 
parts,  powdered  glass  2. 

The  glass  melts  on  exposure  to  great  heat  and  slags  the 
clay  to  a  hard  mass.  The  same  effect  is  produced  by  add- 
ing small  quantities  of  soda  and  borax  to  the  clay.  An 
admixture  of  chalk  and  boric  acid,  as  in  the  following  re- 
ceipt, also  gives  excellent  results. 

II.  Clay  100  parts,  chalk  2,  boric  acid  3. 

Cement  resisting  acids.  Melt  rubber  with  double  the 
quantity  of  linseed  oil,  and  then  knead  in  sufficient  bole  to 
form  a  paste.  This  cement  resists  the  action  of  nitric  and 
hydrochloric  acids,  and  can  be  advantageously  used  for 
closing  bottles  containing  them.  As  it  solidifies  very 
slowly,  it  can  readily  be  detached  from  the  bottles,  and 
used  again. 

For  cement  which  is  to  solidify  quickly  on  exposure  to 
the  air,   add  a  few  per  cent,   by  weight  of  red   lead   or 
litharge. 
'  Rubber  cement  for  chemical  apparatus.     Cut  8  parts  of  rub- 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       249 

ber  in  small  pieces  and  throw  them  gradually  into  a  mix- 
ture of  2  parts  of  tallow  and  16  of  linseed  oil  previously 
strongly  heated.  After  effecting  an  intimate  mixture  of 
the  constituents  by  vigorous  and  constant  stirring,  add  3 
parts  of  white  bole. 

Although  this  cement  does  not  stand  a  high  temperature, 
it  possesses  an  extraordinary  power  of  resisting  the  action 
of  acid  vapors. 

Scheibler's  cement  for  chemical  apparatus.  Melt  together  1 
part  of  wax  and  3  of  shellac,  and  work  into  the  mixture  2 
parts  of  gutta-percha  cut  up  in  very  small  pieces.  This 
cement  will  bear  considerable  heat  without  actually  melting.  / 

CEMENTS    FOR    SPECIAL    PURPOSES. 

Cement  for  attaching  metal  letters  to  glass,  marble,  wood,  etc. 
Dissolve  over  a  water-bath  5  parts  of  glue  in  a  mixture  of 
15  parts  of  copal  varnish,  5  parts  of  boiled  linseed  oil,  3 
parts  of  crude  oil  of  turpentine,  and  2  parts  of  rectified  oil 
of  turpentine,  and  add  10  parts  of  slaked  lime  to  the 
mixture. 

Cement  for  joints  of  iron  pipes.  Mix  5  Ibs.  of  coarsely 
powdered  iron  borings,  2  ozs.  of  powdered  sal  ammoniac, 
and  1  oz.  of  sulphur  with  sufficient  water  to  form  a  paste. 
This  composition  hardens  rapidly,  but  if  time  can  be 
allowed  it  sets  more  firmly  without  the  sulphur.  It  must 
be  used  as  soon  as  mixed,  and  rammed  tightly  into  the 
joint. 

Another  receipt  is  as  follows  : 

Mix  2  ozs.  of  sal  ammoniac,  1  oz.  of  sublimated  sulphur 
and  1  Ib.  of  cast-iron  filings  or  fine  turnings  in  a  mortar, 
and  keep  the  powder  dry.  When  it  is  to  be  used,  mix  it 
with  20  times  its  weight  of  clean  iron  turnings  or  filings 
and  grind  the  whole  in  a  mortar ;  then  wet  it  with  water 
until  it  becomes  of  convenient  consistency,  when  it  is  to  be 
applied  to  the  joint.  After  a  time  it  becomes  as  hard  and 
strong  as  the  metal. 


250  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Steam  boiler  cement.  Mix  10  parts  of  finely-powdered 
litharge  with  1  part  of  fine  sand  and  1  part  of  air-slaked 
lime.  The  mixture  may  be  kept  for  any  length  of  time 
without  deterioration.  For  use  a  portion  of  it  is  made  into 
a  paste  with  linseed  oil  or,  better,  boiled  linseed  oil.  In 
this  state  it  must  be  applied  quickly,  as  it  soon  becomes 
hard. 

Cement  for  rubber.  Powdered  shellac  is  softened  in  10 
times  its  weight  of  strong  water  of  ammonia,  whereby  a 
transparent  mass  is  obtained,  which  becomes  fluid  after 
keeping  some  little  time  without  the  use  of  hot  water.  In 
three  to  four  weeks  the  mixture  is  perfectly  liquid,  and 
when  applied  it  will  be  found  to  soften  the  rubber.  As 
soon  as  the  ammonia  evaporates  it  hardens  again,  and  thus 
becomes  impervious  both  to  gases  and  to  liquids.  For 
cementing  sheet  rubber,  or  rubber  material  in  any  shape, 
to  metal,  glass,  and  other  smooth  surfaces,  this  cement  is 
highly  recommended.] 

Cement  for  tires.  1.  Isinglass  1  oz.,  gutta-percha  1  oz., 
rubber  2  ozs.,  carbon  disulphide  8  fluid  ozs.  Mix  and  dis- 
solve. 

2.  Shellac  4  ozs.,  gutta-percha  4  ozs.,  red  lead  and  sul- 
phur, each  J  oz.     Melt  the   shellac   and  gutta-percha,   and 
add  with  constant  stirring  the  red  lead  and  sulphur,  melted. 
Use  while  hot. 

3.  Crude  rubber  1  oz.,  carbon  disulphide  8  ozs.     Macerate 
24  hours,  and  then  add  a  solution  of: 

Rosin  2  ozs.,  beeswax  J  oz.,  carbon  disulphide  8  ozs. 

4.  Rubber  20  parts,  rosin  10,  Venetian  red  10,  tallow 
5.     Melt  the  rubber  over  a  fire,  then  add  the  rosin  and  the 
tallow  and  finally  the  Venetian  red. 

Cement  for  steam  pipes,  etc.  A  cement  of  specially  valu- 
able properties  for  steam  pipes,  in  filling  up  small  leaks, 
such  as  a  blow-hole  in  a  casting,  without  the  necessity  of 
removing  the  injured  piece,  is  composed  of  5  Ibs.  Paris 
white  and  5  Ibs.  yellow  ochre,  10  Ibs.  litharge,  5  Ibs.  red 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       251 

lead  and  4  Ibs.  black  oxide  of  manganese.  Mix  the  mater- 
ials thoroughly  and  make  into  a  paste  with  a  small  quan- 
tity of  asbestus  and  boiled  linseed  oil.  The  composition,  as 
thus  prepared,  will  harden  in  from  2  to  5  hours,  and  has 
the  advantage  of  not  being  subject  to  expansion  and  con- 
traction to  such  an  extent  as  to  cause  a  leakage  afterwards, 
and  its  efficiency  in  places  difficult  of  access  is  of  special 
importance. 

Cement  for  marble.  Stir  to  a  thick  batter  with  silicate  of 
soda  12  parts  of  Portland  cement,  6  of  slaked  lime,  6  of  fine 
white  lead  and'  1  of  infusorial  earth.  This  is  excellent  for 
marble  and  alabaster.  The  cemented  objects  need  to  be 
heated.  After  24  hours  the  fracture  is  firm,  and  the  place 
can  scarcely  be  found. 

Cement  for  attaching  wood,  glass,  etc.,  to  metal.  Acetate  of 
lead  23  parts  by  weight,  alum  23,  gum  arabic  38,  wheat 
flour  250. 

Dissolve  the  acetate  of  lead  and  the  alum  in  a  little 
water  and  separately  dissolve  the  gum  arabic  in  a  fair 
quantity  of  boiling  water.  Thus  if  the  250  parts  of  wheat 
flour  represent  half  a  pound,  the  quantity  of  water  needed 
will  be  about  a  pint.  The  gum  having  dissolved,  add  the 
flour,  put  the  whole  on  the  fire,  stir  well  with  a  wooden 
stick,  then  add  the  solution  of  lead  acetate  and  alum.  Con- 
tinue the  stirring  in  order  to  avoid  the  formation  of  lumps, 
then  take  it  off  the  fire  without  allowing  it  to  boil.  This 
cement  is  used  cold,  and  will  not  scale.  It  is  very  useful 
in  making  wood,  glass,  cardboard,  etc.,  adhere  to  metal, 
and  is  extremely  strong. 

Brushmakers'  cement.  Rosin  5  Ibs.,  rosin  oil  or  spirit  1 
quart. 

Reduce  the  rosin  to  small  pieces,  run  down  in  a  pot,  add 
the  other  ingredient,  and  stir  until  mixed  and  syrupy,  then 
run  out  into  tins.  It  is  used  for  cementing  the  bristles  in 
the  stocks,  also  for  string  binding  on  sash  tools,  etc. 

Cement  for   electrical  apparatus.     Mix  together  1   Ib.   of 


252  GLUE,    GELATINE,    CEMENTS,    PASTES. 

beeswax  added  to  5  Ibs.  of  rosin,  1  Ib.  of  red  ochre,  and  2 
tablespoonfuls  of  plaster  of  Paris.  It  will  make  an  excel- 
lent composition  for  electrical  apparatus. 

A  cheaper  composition  for  cementing  voltaic  plates  into 
wooden  troughs  is  made  with  6  Ibs.  of  plaster  of  Paris  and 
J  pint  of  linseed  oil.  The  ochre  and  the  plaster  of  Paris 
should  be  well  dried  and  added  to  the  other  ingredients 
when  these  are  in  a  melted  state. 

Jewelers'  cement.  Dissolve  over  the  water-bath  25  parts 
of  fish  glue  in  a  small  quantity  of  strong  spirits  of  wine, 
add  2  parts  of  gum  ammoniac ;  separately  dissolve  1  part 
of  mastic  in  5  of  spirits  of  wine.  Mix  the  two  solutions 
and  keep  them  in  well-stoppered  bottles. 

American  cement  for  jeivelers.  Soak  4  ozs.  of  isinglass  in 
2  Ibs.  of  water  for  24  hours,  then  evaporate  in  the  water- 
bath  ;  to  1  Ib.  add  1  Ib.  of  rectified  spirits  of  wine,  and 
strain.  Then  mix  in  a  solution  of  2  ozs.  of  mastic  and  1 
oz.  of  gum  ammoniac  in  16  ozs.  of  rectified  spirit. 

Cement  for  celluloid.  Shellac  2  ozs.,  spirits  of  camphor  2, 
90  per  cent,  alcohol  6  to  8. 

Stratena.  This  well-known  household  cement  is  said  to 
be  prepared  as  follows:  Dissolve  12  parts  of  white  glue  in 
16  of  acetic  acid,  and  then  add  this  solution  to  one  of  2 
parts  gelatine  in  16  of  water.  After  mixing  add  2  parts 
shellac  varnish. 

Cement  for  cloth.  Gutta-percha  16  parts,  rubber  4,  pitch 
2,  shellac  1,  linseed  oil  2  pints.  Dissolve  the  whole  by 
heat,  stirring  constantly. 

HOW    TO    USE    CEMENTS. 

It  is  unquestionably  true  that  quite  as  much  depends 
upon  the  manner  in  which  a  cement  is  applied,  as  upon  the 
cement  itself.  The  best  cement  that  was  ever  compounded 
would  prove  entirely  worthless  improperly  applied.  In 
the  foregoing  a  number  of  cements  have  been  given  which 
answer  every  reasonable  demand  when  properly  prepared 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       253 

and  properly  used.  Good  common  glue  will  unite  two 
pieces  of  wood  so  firmly  that  the  fibres  will  part  from 
each  other  rather  than  from  the  cementing  material ;  two 
pieces  of  glass  can  be  so  joined  that  they  will  part  any- 
where rather  than  on  the  line  of  union;  glass  can  be  united 
to  metal,  metal  to  metal,  stone  to  stone,  and  all  so  strongly 
that  the  joint  will  certainly  not  be  the  weakest  part  of  the 
resulting  mass.  What  are  the  rules  to  be  observed  in 
effecting  these  results  ? 

The  first  point  that  demands  attention  is  to  bring  the 
cement  itself  into  intimate  contact  with  the  surface  to  be 
united.  If  glue  is  employed,  the  surface  should  be  made 
so  warm  that  the  melted  glue  will  not  be  chilled  before  it 
has  time  to  effect  a  thorough  adhesion.  The  same  is  more 
eminently  true  in  regard  to  cements  that  are  used  in  a  fused 
state,  such  as  mixtures  of  resins,  shellac,  and  similar 
materials.  These  matters  will  not  adhere  to  any  substance 
unless  the  latter  has  been  heated  to  nearly  or  quite  the 
fusing  point  of  the  cement  used.  This  fact  was  quite 
familiar  to  those  who  used  sealing-wax  in  the  olden  days 
of  seals.  When  the  seal  was  used,  in  succession,  rapidly  so 
as  to  become  heated,  the  sealing-wax  stuck  to  it  with  a 
firmness  that  was  annoying,  so  much  so  that  the  impression 
was  generally  destroyed,  from  the  simple  fact  that  the 
sealing-wax  would  rather  part  in  its  own  substance  than  at 
the  point  of  adhesion  to  the  seal.  Sealing-wax  or  ordinary 
so-called  electric  cement  is  a  very  good  agent  for  uniting 
metal  to  glass  or  stone,  provided  the  masses  to  be  united 
are  made  so  hot  as  to  fuse  the  cement ;  but  if  the  cement  is 
applied  to  them  while  they  are  cold,  it  will  not  stick  at  all. 
This  fact  is  well  known  to  those  itinerant  venders  of  cement 
for  uniting  earthenware.  By  heating  two  pieces  of  delf  so 
that  they  will  fuse  shellac,  they  are  able  to  smear  them 
with  a  little  of  this  gum  and  join  them  so  that  they  will 
rather  break  at  any  other  part  than  along  the  line  of  union. 
But  although  people  see  the  operation  constantly  performed 


254  GLUE,    GELATINE,    CEMENTS,    PASTES. 

and  buy  liberally  of  the  cement,  it  will  be  found  that  in 
nine  cases  out  of  ten,  the  cement  proves  worthless  in  the 
hands  of  the  purchasers,  simply  because  they  do  not  know 
how  to  use  it.  They  are  afraid  to  heat  a  delicate  glass  or 
porcelain  vessel  to  a  sufficient  degree,  and  they  are  apt  to 
use  too  much  of  the  material,  and  the  result  is  a  failure. 

The  great  obstacles  to  the  junction  of  any  two  surfaces 
are  air  and  dirt.  The  former  is  universally  present,  while 
the  latter  is  due  to  accident  or  carelessness.  All  surfaces 
are  covered  with  a  thin  adhering  layer  of  air,  which  it  is 
difficult  to  remove,  and  which,  although  it  may  at  first 
sight  seem  improbable,  bears  a  relation  to  the  outer  surface 
of  most  bodies  different  from  that  maintained  by  the  air  a 
few  lines  away.  The  reality  of  the  existence  of  this  adher- 
ing layer  of  air  is  well  known  to  all  who  are  familiar  with 
electrotype  manipulation.  It  is  also  seen  in  the  case  of 
highly  polished  metals  which  may  be  immersed  in  water 
without  becoming  wet.  Unless  this  adhering  layer  of  air 
is  displaced,  the  cement  cannot  adhere  to  the  surface  to 
which  it  is  applied  because  it  cannot  come  in  contact  with 
it.  The  most  efficient  agent  in  displacing  this  air  is  heat. 
Metals  warmed  to  a  point  a  little  above  203°  F.  become 
instantly  and  completely  wet  when  immersed  in  water. 
Hence,  for  cements  that  are  used  in  a  fused  condition,  heat 
is  the  most  efficient  means  of  bringing  them  in  contact  with 
the  surfaces  to  which  they  are  to  be  applied.  Another  very 
important  point  is  to  use  as  little  cement  as  possible. 
When  the  surfaces  are  separated  by  a  large  mass  of  cement 
we  have  to  depend  upon  the  strength  of  the  cement  itself 
and  not  upon  its  adhesion  to  the  surfaces  which  it  is  used 
to  join  ;  and,  in  general,  cements  are  comparatively  brittle. 

The  cement  forced  out  of  the  joint  by  pressing  the  sur- 
faces together  should  be  removed  while  the  cement  is  in  a 
fused  state  or  liquid.  This  can  generally  be  effected  by 
wiping  the  surplus  off,  while  after  solidification  a  certain 
amount  of  force  has  to  be  used  which  may  frequently  break 
the  joint. 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.        255 

Oil  cements,  which  generally  solidify  slowly,  have  the 
advantage  of  being  water-proof.  In  cementing  with  oil 
cements,  coat  the  surfaces  to  be  joined  with  linseed  oil,  or, 
still  better,  boiled  linseed  oil,  but  in  working  with  resinous 
cements  apply  oil  of  turpentine,  spirit  of  wine,  or  a  fluid 
which  will  readily  dissolve  the  cementing  constituent  of  the 
cement. 

For  cleansing  the  surfaces  from  grease  and  dirt  place  the 
articles  in  strong  lye  and  rinse  off  in  clean  water  without 
touching  the  surfaces  with  the  hands.  For  painted  por- 
celain articles  which  cannot  be  placed  in  lye,  it  is  recom- 
mended to  brush  the  surfaces  several  times  with  carbon 
disulphide. 

PASTES    AND    MUCILAGES. 

Preparation  of  paste.  Ordinary  paste  is  prepared  either 
from  flour  or  starch,  and  according  to  the  raw  material 
used  in  its  preparation,  may,  therefore,  be  divided  into 
starch  and  flour  paste. 

Starch  is  an  indispensable  constituent  of  certain  parts  of 
plants,  and  plays  an  important  part*  in  the  nutrition  of  the 
plant.  It  is  chiefly  manufactured  from  potatoes,  Indian 
corn  and  grain.  Examined  under  the  microscope,  it  is 
seen  to  be  composed  of  small  granules  consisting  of  layers 
placed  one  above  the  other. 

Starch  paste.  In  stirring  starch  with  water  to  a  thin 
paste  and  gradually  heating  it,  it  will  be  observed  that  at  a 
temperature  between  140°  and  158°  F.  a  peculiar  change 
takes  place ;  the  thin  milk-white  liquid  becomes  trans- 
parent, opalizes,  and  at  the  same  time  becomes  thickly  fluid, 
in  short,  the  starch  is  converted  into  paste.  During  this 
process  the  separate  layers  of  the  starch  granules  become 
detached  somewhat  in  the  same  manner  as  an  opening  bud, 
whereby  they  absorb  water,  and  the  peculiar  mass,  called 
paste,  is  formed.  That  paste  is  not  a  solution  is  easily 
proved  by  the  fact  that  on  attempting  to  filter  starch-paste 


256  GLUE,    GELATINE,    CEMENTS,    PASTES. 

only  water  drains  off,  while  the  starch  remains  upon  the 
filter  and  gradually  dries  to  a  horny  mass. 

Paste  left  to  itself  soon  decomposes,  especially  during  the 
hot  season  of  the  year ;  it  becomes  sour  through  the  forma- 
tion of  lactic  acid,  butyric  acid,  acetic  acid,  and  other  sub- 
stances, and  loses  its  adhesive  power. 

In  preparing  paste,  the  following  rules  must  be  especially 
observed  :  Divide  the  starch  in  water  by  constant  stirring 
so  as  to  form  a  homogeneous,  rather  thinly  liquid  fluid,  and 
then  add  boiling  water  in  small  portions,  stirring  constantly. 
The  conversion  of  the  starch  into  paste  is  recognized  by  the 
thickening  of  the  entire  mass  and  the  appearance  of  opal- 
escence,  when  it  is  only  necessary  to  add  the  required  quan- 
tity of  water  to  give  the  paste  the  desired  consistency. 

If  white  lumps  are  observed,  it  is  an  indication  that  the 
starch  has  not  been  thoroughly  mixed  with  the  water,  and 
that  certain  portions  of  it  have  remained  dry.  Paste  con- 
taining such  lumps  cannot  be  applied  with  any  degree  of 
uniformity,  and  besides  it  possesses  less  adhesive  power. 
Nothing  can  be  done  to  remedy  the  evil  except  diluting  the 
paste  with  a  considerable  quantity  of  water  and  boiling, 
with  constant  stirring,  until  the  mass  is  perfectly  homo- 
genous. 

Starch  paste  prepared  in  a  proper  manner  possesses  great 
adhesive  power,  and,  when  applied  in  a  thin  layer,  dries  to 
an  almost  colorless  coating.  Pure  starch  paste  is  used  for 
many  purposes.  It  serves  not  only  for  pasting  paper,  wall 
paper,  etc.,  but  also  for  sizing  tissues,  such  as  paper-muslin, 
linen,  etc.,  in  order  to  give  them  lustre,  body,  and,  under 
certain  circumstances,  greater  weight.  To  increase  the 
weight  of  linen,  white  lead  or  heavy  spar  is  frequently 
mixed  with  the  starch. 

Flour  paste.  The  principal  constituent  of  flour,  besides 
starch,  is  gluten.  It  is  obtained  in  a  pure  state  by  tying 
flour  in  a  linen  bag  and  kneading  it  under  water  so  long 
as  the  latter  is  rendered  turbid  by  particles  of  starch.  The 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       257 

gluten  remaining  in  the  bag  is  a  light-brown,  very  tenacious 
mass,  drawing  threads  between  the  fingers,  and,  as  regards 
its  chemical  properties,  is  closely  allied  to  albumen  and 
caseine.  Gluten,  like  the  last-mentioned  substances,  shows 
a  tendency  to  form  combinations  with  lime  which  gradually 
solidify,  and  it  can  therefore  be  used  for  preparing  cements. 
Like  albumen  and  caseine,  it  speedily  putrefies  if  exposed 
to  the  air  in  a  moist  state,  and  in  decomposing  forms  pro- 
ducts which  have  a  very  unpleasant  odor. 

Flour  paste  is  prepared  in  precisely  the  same  manner  as 
starch  paste,  but  while  the  latter  is  white,  flour  paste,  even 
if  prepared  from  the  best  wheat  flour,  has  always  a  yellow- 
brown  color.  As  regards  adhesive  power  it  is  superior  to 
starch  paste,  but  is  less  durable. 

There  are  many  means  to  prevent  the  spoiling  of  paste. 
With  paste  once  dry  and  kept  so,  there  is  no  danger  of 
spoiling,  but  if  it  is  alternately  exposed  to  dampness  and 
dryness,  as  for  instance  with  wall-paper  hung  on  walls  not 
entirely  dry,  decomposition  will  unavoidably  take  place, 
and  the  wall  paper  will  become  spotted  and  fall  off  the  wall. 

Provided  either  starch  or  flour  paste  is  protected  against 
drying  in,  it  can  be  kept  unchanged  for  a  long  time  by  the 
addition  of  a  small  quantity  of  carbolic  acid. 

For  hanging  wall-paper  an  addition  of  alum  is,  generally 
speaking,  more  suitable  than  carbolic  acid. 

In  hanging  wall-paper  the  wall  is  generally  first  sized 
with  glue  water.  By  the 'alum  coming  in  contact  with  glue 
an  insoluble  leather-like  combination  is  formed,  which  not 
only  resists  decomposition,  but  by  far  surpasses  ordinary 
paste  as  regards  adhesive  power,  so  that  when  the  paper  is 
to  be  removed  from  the  wall  it  has  to  be  scraped  and  torn 
off  in  small  pieces,  while  that  hung  without  previous  sizing 
of  the  wall  is  readily  removed  in  large  pieces. 

But  alum  cannot  be  used  for  preserving  a  glue  solution, 
as  it  would  cause  it  to  coagulate  to  a  flaky  mass.     Carbolic 
acid  is,  on  the  other  hand,  an  excellent  means  for  the  pur- 
17 


258  GLUE,    GELATINE,    CEMENTS,    PASTES. 

pose,  but  to  prevent  its  characteristic  empyreumatic  odor 
from  making  itself  too  sensibly  felt,  no  more  than  about 
one  two-thousandth  of  the  weight  of  the  glue  solution  should 
be  added. 

Shoemakers'  paste.  In  addition  to  being  cheap,  no  other 
paste  adheres  as  well  to  leather  as  the  so-called  shoemakers' 
paste.  With  it  leather  can  be  secured  not  only  to  leather, 
but  also  to  woven  materials,  paper,  etc.  Though  its  prepar- 
ation is  very  simple,  it  is  connected  with  some  disagreeable 
features  consisting  chiefly  in  the  development  of  a  truly 
terrible  stench. 

The  paste  is  prepared  by  stirring  crushed  barley  with 
hot  water  to  a  thick  paste  and  adding  small  portions  of  hot 
water,  so  that  the  temperature  of  the  mass  is  kept  at  between 
86°  to  104°  F.  In  a  few  days  the  mass  commences  to 
develop  gas,  which  shows  at  first  no  odor,  but  soon  the 
development  of  gas  becomes  stronger  and  an  acid  odor  is 
perceptible,  which  in  a  short  time  is  replaced  by  a  terrific 
stench  which,  as  before  mentioned,  affects  the  olfactory 
organs  in  a  most  unpleasant  manner. 

In  consequence  of  the  acid  and  putrid  fermentation  the 
pasty  mass  gradually  loses  its  granular  condition,  and  is 
finally  converted  into  a  homogeneous,  thickly  fluid  mass  of 
a  brown  color,  which  draws  threads  between  the  fingers, 
and  possesses  great  adhesive  power.  When  this  is  the  case, 
decomposition,  wrhich  otherwise  would  go  on  until  nothing 
remained  but  a  watery  and  acid  fluid,  is  interrupted  by 
lowering  the  temperature  of  the  paste  by  ladling  it  from  the 
vat  or  by  adding  a  small  quantity  of  carbolic  acid. 

To  render  the  stench  developed  during  the  fermentation 
of  the  paste  innoxious,  the  vat  in  which  it  is  prepared 
should  be  provided  with  a  well-fitting  cover,  in  which  is 
fitted  a  stovepipe  passing  into  a  chimney  connected  with  a 
kitchen  range  or  furnace,  in  which  a  fire  is  frequently  burnt. 

By  kneading  shoemaker's  paste  together  with  indifferent 
substances  it  can  be  used  as  a  cement  for  various  purposes. 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES. 

The  substances  best  adapted  for  the  purpose  are  burnt  lime 
slaked  to  a  powder,  whiting,  zinc  white,  pipe  clay,  ochre,  etc. 

Gum  arable.  This  gum  is  an  exudation  from  certain 
tropical  species  of  acacia,  and  consists  essentially  of  arabine, 
which  has  the  composition  C12H11Oi1.  The  best  gum 
arabic  is  that  in  the  form  of  very  pale-yellow,  brittle  pieces  ; 
golden-yellow  to  brownish  pieces  are  not  valued  as  highly, 
though  they  give  a  solution  of  considerable  adhesive  power. 

Gum  arabic  dissolves  in  water,  but  not  in  alcohol,  and 
therefore  can  not  be  employed  for  cements  in  the  prepara- 
tion of  which  solutions  of  resins  in  spirit  of  wine  are  to  be 
used. 

There  are  other  products  of  vegetable  life,  which  are  also 
in  commerce,  called  gums,  but  dissolve  partly  in  spirit  of 
wine.  To  this  class  belongs  the  gum  ammoniac  mentioned 
in  some  receipts  for  cements.  As  it  is  rather  expensive,  it 
is  seldom  used  by  itself  as  a  cement. 

Dextrine  is  extensively  used  in  place  of  gum  arabic  in 
printing  wall-papers,  for  stiffening  and  glazing  cards  and 
paper,  for  thickening  the  colors  of  calico  printers,  in  mak- 
ing mucilages,  etc.  It  is  prepared  by  heating  starch  pre- 
viously moistened  with  nitric  acid  in  an  oven,  and  can  also 
be  produced  by  heating  paste  with  malt  extract  or  very 
dilute  sulphuric  acid.  There  is  a  current  anecdote  which 
attributes  the  discovery  of  dextrine  to  a  conflagration  at  a 
starch  factory  where  one  of  the  workmen  who  assisted  in 
quenching  the  fire  observed  the  gummy  properties  of  the 
water  which  had  been  thrown  over  the  torrefied  starch. 

Commercial  dextrine  forms  pale-yellow  to  dark-brown 
masses.  These  masses  dissolve  readily  in  water,  and  form 
solutions  which,  as  regards  adhesive  power,  compare  favor- 
ably with  those  prepared  from  gum  arabic.  The  mucilage 
is  prepared  by  simply  stirring  the  pulverized  dextrine  with 
water  to  a  thickly-fluid  liquid. 

To  preserve  mucilage  unchanged  for  any  length  of  time, 
and  to  prevent  the  disagreeable  formation  of  mould  upon 


260  GLUE,    GELATINE,    CEMENTS,    PASTES. 

its  surface,  it  is  recommended  to  dissolve  some  salicylic  acid 
in  the  water  to  be  used  for  preparing  the  mucilage. 

Dextrine  is  usually  prepared  on  a  large  scale  by  moistening 
10  parts  of  starch  with  3  parts  of  water  acidulated  with  T^ 
part  of  nitric  acid.  The  mixture  is  allowed  to  dry,  and  is 
then  spread  upon  trays  in  layers  about  three-quarters  of  an 
inch  deep  in  an  oven,  where  it  is  heated  for  about  one  hour 
to  239°  F.  Sometimes  large  drums  revolving  over  a  fire 
are  used,  or,  in  order  to  keep  up  a  uniform  temperature,  the 
starch  is  placed  in  a  copper  cylinder  suspended  in  a  vessel 
with  oil  which  is  heated  to  356°  F.  The  object  of  the  ad- 
dition of  nitric  acid  is  to  allow  the  starch  to  be  converted 
into  dextrine  at  a  temperature  which  would  be  inadequate 
to  effect  the  transformation  of  starch  alone. 

Dextrine  is  also  frequently  prepared  by  allowing  germin- 
ated barley  or  malt  to  act  upon  starch.  Heat  350  to  400 
parts  of  water  to  about  77°  F.,  and  after  adding  5  to  10 
parts  of  dry  malt,  raise  the  temperature  to  140°  F.  Then 
add  100  parts  of  starch,  and  after  mixing  the  whole  thor- 
oughly together,  raise  the  temperature  to  about  158°  F.  for 
twenty  minutes.  The  mass,  which  appears  at  first  milky 
and  sticky,  will  gradually  become  as  liquid  as  water  by  the 
conversion  of  the  starch  into  gum  through  the  action  of  the 
malt.  To  prevent  the  conversion  of  the  gum  into  sugar  by 
the  diastase  of  the  malt,  the  fluid  must  be  quickly  brought 
to  the  boiling-point,  and,  after  cooling,  filtered  and  evapor- 
ated to  the  consistency  of  syrup.  In  cooling,  the  mass  gela- 
tinizes to  a  jelly,  which  after  drying  is  hard  and  brittle. 

According  to  Blumenthal's  method,  a  drum  which  can 
be  hermetically  closed,  is  filled  two-thirds  full  with  dry 
starch  flour  by  means  of  a  funnel.  A  stirring  apparatus  is 
then  set  in  motion,  and  the  acid  which  is  contained  in  a 
graduated  cylinder  is  sprayed  into  the  drum  by  means  of  a 
special  contrivance. 

In  a  drum  5  feet  long  and  3J  feet  in  diameter,  220  Ibs. 
of  potato  starch  can  be  uniformly  mixed  in  5  minutes  with 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       261 

about  9  ozs.  of  nitric  acid  of  40°  B.,  and  the  drum  emptied 
by  opening  the  slide.  Starch  thus  treated  may  be  brought 
into  the  oven  without  previous  drying. 

Heuze'  gives  the  following  method  :  Four  and  a  half 
pounds  of  nitric  acid  of  1.4  specific  gravity  together  with 
300  quarts  of  water  are  mixed  with  2,200  Ibs.  of  starch,  and 
boiled  to  form  a  mass  which,  when  exposed  to  the  air  be- 
comes dry.  It  is  sometimes  effected  at  177°  F.,  but  it 
becomes  a  paste  at  212°  to  230°  F.  The  starch  changes 
into  dextrine  in  an  hour  or  an  hour  and  a  half  at  the  most; 
it  is  white  and  soluble  in  water. 

Tragacanth,  or  gum  tragacanth,  exudes  from  Astragalus 
verus,  a  tree  indigenous  to  Asia.  The  term  gum  is  a  mis- 
nomer, as  tragacanth  does  not  actually  dissolve  in  water 
nor  in  spirit  of  wine,  but  merely  swells  up  in  water  to  a  soft 
gelatinous  mass.  Tragacanth  consists  of  irregular  pieces  of 
a  pure  white  to  yellowish  color.  It  is  chiefly  used  for  con- 
fectioner's purposes,  though  sometimes  as  a  paste  for  fancy 
articles.  This  variety  of  gum  is  found,  together  with 
arabine,  in  the  gum  which  exudes  from  cherry,  plum, 
almond,  and  apricot  trees,  and  gives  the  mucilaginous  char- 
acter to  the  watery  decoctions  prepared  from  certain  seeds, 
such  as  linseed  and  quince-seed,  and  from  the  root  of 
marshmallow. 

PASTES    AND    MUCILAGES    FOR    SPECIAL   PURPOSES. 

Starch  paste.  Corn  starch  8  ozs.,  cold  water  J  pint;  boil- 
ing water  1  gallon. 

Beat  up  the  starch  in  the  cold  water  until  reduced  to  a 
creamy  consistence,  then  pour  the  mixture  into  the  boiling 
water  and  stir  briskly  until  the  white,  semi-opaque  mass, 
becomes  transparent.  Should  it  fail  to  do  so,  place  it  over 
the  fire,  and  boil  until  the  desired  result  is  obtained,  stirring 
constantly. 

Flour  paste.  Wheat  flour  4  Ibs.,  cold  water  2  quarts, 
alum  2  ozs.,  hot  water  \  pint,  boiling  water  2  gallons. 


262  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Work  the  wheat  flour  into  a  batter  free  from  lumps  with 
the  cold  water.  Dissolve  the  alum  in  the  hot  water.  Then 
stir  the  batter  into  the  boiling  water,  and  if  necessary,  con- 
tinue boiling  until  the  paste  thickens  into  a  semi-transparent 
mucilage,  after  which  stir  in  the  alum  solution.  This 
makes  a  very  fine  paste  for  wall-paper. 

Strong  adhesive  paste.  Rye  flour  2  Ibs.,  cold  water  1 
quart,  boiling  water  3  quarts,  pulverized  rosin  1  oz. 

Make  the  flour  into  a  batter  with  the  cold  water,  free 
from  lumps,  and  pour  into  the  boiling  water.  Boil,  if 
necessary,  and  while  hot  stir  in  the  pulverized  rosin,  a 
little  at  a  time.  This  paste  is  very  strong,  and  will  fasten 
heavy  wall-paper  or  thin  leather.  If  too  thick,  thin  with 
hot  water.  Never  thin  paste  with  cold  water. 

Paste  that  will  not  sour.  Allow  4  parts  by  weight  of  glue 
to  soften  in  15  parts  of  cold  water  for  some  hours,  and  then 
heat  moderately  till  the  solution  becomes  quite  clear ;  then 
add,  while  stirring,  65  parts  of  boiling  water.  In  another 
vessel  stir  up  30  parts  of  starch  paste  with  20  parts  of  cold 
water,  so  that  a  thin,  milky  fluid  without  lumps  is  obtained. 
Into  this  pour  the  boiling  glue  solution,  stirring  constantly, 
and  keep  the  whole  at  the  boiling  temperature.  After  cool- 
ing, add  5  to  10  drops  of  carbolic  acid  to  the  paste.  Pre- 
serve the  paste  in  closed  bottles  to  prevent  evaporation  of 
the  water.  It  will  thus  keep  good  for  years. 

Venetian  paste.  White  or  fish  glue  4  ozs.,  cold  water  J 
pint,  Venice  turpentine  2  fluid  ozs.,  rye  flour  1  lb.,  cold 
water  1  pint,  boiling  water  2  quarts. 

Soak  the  4  ozs.  of  glue  in  the  cold  water  for  4  hours. 
Dissolve  over  a  water-bath,  and  while  hot  stir  in  the  Venice 
turpentine.  Make  up  the  rye  flour  into  a  batter  free  from 
lumps  with  the  pint  of  water,  and  pour  the  latter  into  the 
boiling  water.  Stir  briskly,  and  finally  add  the  glue  solu- 
tion. This  makes  a  very  strong  paste,  and  it  will  adhere 
to  a  painted  surface,  owing  to  the  Venice  turpentine  in  its 
composition. 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       263 

Label  paste.  A  good  paste  for  attaching  labels  to  bottles 
may  be  made  by  soaking  glue  in  strong  vinegar,  then  heat 
to  boiling  and  add  flour.  This  is  very  adhesive,  and  will 
not  decompose  when  kept  in  wide-mouthed  bottles. 

Elastic  or  pliable  paste.  Starch  4  ozs.,  white  dextrine  2 
ozs.,  cold  water  10  fluid  ozs.,  borax  1  oz.,  glycerine  3  fluid 
ozs.,  boiling  water  2  quarts. 

Beat  the  starch  and  dextrine  into  paste  with  the  cold 
water.  Dissolve  the  borax  in  the  boiling  water,  then  add 
the  glycerine,  and  pour  the  starch  and  dextrine  mixture 
into  the  borax  solution.  Stir  until  it  becomes  translucent. 
This  paste  will  not  crack,  and,  being  very  pliable,  is  suit- 
able for  paper,  cloth,  leather  and  other  material  where 
flexibility  is  required. 

Mucilage  for  labels.  Macerate  5  parts  of  good  glue  in  20 
parts  of  water  for  24  hours,  and  to  the  liquid  add  9  parts  of 
rock  candy,  and  3  parts  of  gum  arabic.  The  mixture  may 
be  brushed  upon  paper  while  lukewarm.  It  keeps  well, 
does  not  stick  together  and  adheres  firmly  to  bottles. 

Mucilage.  A  strong  aqueous  solution  of  dextrine  forms  a 
most  adhesive  and  cheap  mucilage.  Dilute  alcohol  is 
usually  employed  as  the  solvent  where  the  mucilage  is  to 
be  used  for  gumming  envelopes,  postage  stamps,  etc.,  and  in 
order  to  facilitate  the  drying,  acetic  acid  is  added  to  in- 
crease the  mobility  of  the  fluid.  The  strong  aqueous  solu- 
tion is  more  adhesive  than  that  prepared  with  alcohol,  for 
the  reason  that  it  contains  a  greater  proportion  of  dextrine. 

To  prepare  this  add  an  excess  of  dextrine  to  boiling 
water,  stir  for  a  minute  or  two,  allow  to  cool  and  settle,  and 
strain  the  liquid  through  a  cloth.  The  addition  of  a  little 
powdered  sugar  increases  the  glossiness  of  the  dried  gum. 
The  sugar  should  be  dissolved  in  the  water  before  the  dex- 
trine is  added. 

According  to  another  formula,  dextrine  is  mixed  with  hot 
water  until  a  syrupy  liquid  is  obtained.  Then  add  a  few 
drops  of  oil  of  cloves,  and  cool  for  use. 


264  GLUE,    GELATINE,    CEMENTS,    PASTES. 

Another  formula  is  as  follows:  Dextrine  120  parts,  powdered 
alum  6,  sugar  30,  carbolic  acid  1,  water  300.  Mix  gradu- 
ally the  dextrine,  alum  and  sugar  with  the  water,  boil  to 
effect  solution,  and  when  cold,  add  the  carbolic  acid. 

The  solubility  of  dextrine  may  be  enhanced  by  the  addi- 
tion of  a  calcium  salt  readily  soluble  in  water,  the  resulting 
mixture  dissolving  with  ease  in  cold  water.  Calcium 
nitrate  has  proved  especially  suitable  for  the  purpose.  By 
pouring  1  quart  of  water  over  a  mixture  of  18  ozs.  of  dex- 
trine and  7  ozs.  of  calcium  nitrate,  a  mass  of  great  adhesive 
power  is  immediately  obtained. 

Mucilage  for  postage  stamps.  Dextrine  2  parts,  acetic  acid 
1,  water  5,  alcohol  1.  Mix  all  together. 

Caseine  mucilage.  Take  the  curd  of  skim  milk,  wash  it 
thoroughly,  and  dissolve  it  to  saturation  in  a  cold  concen- 
trated solution  of  borax. 

Tragacanth  mucilage.  Powdered  tragacanth  2  drachms, 
glycerine  12  drachms,  water  enough  to  make  20  ozs. 

Put  the  tragacanth  in  a  mortar  with  the  glycerine,  and 
then  add  the  water.  This  will  produce  at  once  a  mucilage 
of  excellent  quality. 

Adhesive  paste.  Steep  4  ozs.  of  ordinary  gelatine  in 
16  ozs.  of  water  until  it  becomes  soft,  then  dissolve  it  by  the 
heat  of  a  water  bath,  and  while  still  hot  pour  into  a  mix- 
ture of  2  Ibs.  of  good  flour  paste  and  1  part  of  water.  Heat 
the  whole  to  boiling  and  when  thickened  remove  from  the 
fire.  While  cooling  add  6  drachms  of  silicate  of  soda  and 
stir  the  mixture  with  a  wooden  spatula.  This  preparation 
will  keep  good  for  an  indefinite  period,  and  is  very  adhesive. 
The  addition  of  2  drachms  of  oil  of  cloves  is  an  improve- 
ment. 

Fluid  pastes.  I.  Gum  arabic  10  Ibs.,  sugar  2  Ibs.,  nitric 
acid  If  ozs.,  water  as  required. 

Dissolve  the  gum  and  sugar  in  the  water,  then  add  the 
acid  and  heat  to  the  boiling-point.  The  resulting  paste  is 
liquid,  does  not  mould,  and  dries  to  a  transparent  layer 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       265 

upon  paper.  It  is  especially  suitable  for  flaps  of  envelopes, 
fine  bookbinders'  work,  etc. 

II.  Potato  starch  10  Ibs.,  water  5  quarts,  nitric  acid  8  ozs. 

Mix  the  acid  and  water  and  pour  it  on  the  starch  in  an 
earthenware  basin,  put  the  latter  in  a  warm  place,  and 
allow  it  to  remain  24  hours,  with  occasional  stirring.  Then 
boil  it  until  it  becomes  thickly-fluid  and  very  transparent. 
If  necessary  it  should  be  diluted  with  water  and  filtered 
through  a  cloth. 

Sugar  and  lime  paste.  Dissolve  12  parts  of  white  sugar  in 
36  of  water.  Heat  the  solution  to  the  boiling-point  and 
add  3  parts  of  slaked  lime.  Allow  the  liquid  to  stand  in  a 
covered  vessel  for  several  days,  stirring  frequently  and, 
when  settled,  pour  off  the  supernatant  thick  fluid  from  the 
excess  of  lime. 

The  paste  thus  obtained  has  all  the  properties  of  gum 
arabic  solution  and  dries  to  a  lustrous  mass. 

Liquid  sugar  and  lime  paste.  Allow  3  parts  of  glue  to 
swell  in  10  to  15  parts  of  the  foregoing  paste.  Heat  the 
mixture  to  the  boiling-point.  The  paste  thus  obtained  does 
not  congeal  on  cooling  and  possesses  considerable  adhesive 
power. 

By  reason  of  its  caustic  properties,  due  to  the  content  of 
lime,  this  paste  should  not  be  used  for  pasting  colored 
materials. 

Pastes  for  paper  and  fine  fancy  articles.  I.  Dissolve,  with 
the  assistance  of  heat,  100  parts  of  gilder's  glue  in  200  of 
water,  and  add  a  solution  of  2  parts  of  bleached  shellac  in 
10  of  alcohol. 

II.  Dissolve,  with  the  assistance  of  heat,  50  parts  of  dex- 
trine in  50  of  water,  stir  solutions  1  and  2  together,  strain 
through  a  cloth  into  a  flat  prismatic  mould,  and  allow  it  to 
congeal.  For  use,  melt  a  piece  of  corresponding  size,  and 
dilute  the  liquid,  if  necessary,  with  water. 

Albumen  paste.  This  is  a  misnomer,  as  it  contains  no 
albumen.  It  is  partly  decayed  gluten  from  flour,  washed 


266  GLUE,    GELATINE,    CEMENTS,    PASTES. 

with  water  and  then  heated  to  60°  or  68°  F.,  when  it  fer- 
ments and  becomes  partly  fluid.  It  is  then  dried  at  77°  to 
86°  F.,  and  is  claimed  to  keep  any  length  of  time  in  a  dry 
place.  Dissolved  in  twice  its  weight  of  water  it  can  be  used 
as  a  paste  for  all  purposes. 

Glycerine  paste.  Dissolve  2  ozs.  of  gum  arabic  and  4 
drachms  of  glycerine  in  6  ozs.  of  boiling  water.  This  is  a 
good  paste  for  office  use. 

Paste  for  fixing  labels  on  machines.  Make  a  paste  of  rye 
flour  and  glue  and  add  to  every  pound  thereof  J  oz.  each  of 
boiled  linseed  oil  and  turpentine.  This  paste  resists  damp 
and  thus  prevents  printed  labels  from  falling  off  metallic 
surfaces. 

Paste  for  mounting  maps.  Stiff  rye  flour  paste  is  best  for 
this  purpose. 

Paste  for  fastening  paper  on  tin-foil.  Make  a  paste  by  dis- 
solving rye  flour  in  solution  of  caustic  soda ;  dilute  with 
water,  stirring  all  the  time.  Add  to  this  paste  a  few  drops 
of  Venice  turpentine  for  each  \  Ib.  of  flour. 

Paste  for  paper  bags.  Add  to  3  parts  of  starch  24  to  30 
parts  of -cold  water.  Stir  together  to  a  homogeneous  mass 
of  about  the  thickness  of  syrup.  Pour  over  this,  stirring 
constantly,  boiling  water  until  the  paste  is  of  the  required 
consistency.  Stir  until  nearly  cold.  Take  a  portion  of  the 
paste  and  add  to  it  6  to  15  per  cent,  liquefied  Venice  tur- 
pertine  ;  rub  together  until  a  kind  of  emulsion  is  formed, 
then  mix  the  whole  together  and  work  thoroughly. 

Caseine  mucilage  for  photographer's  use.  Separate  the 
caseine  from  milk  by  means  of  a  little  tartaric  acid,  and 
treat  the  caseine  while  still  warm  with  a  solution  of  6  parts 
of  borax  to  100  parts  water,  and  warm  gently  while  stirring 
which  will  cause  the  caseine  to  be  dissolved.  Of  the  borax 
solution  enough  should  be  used  to  leave  only  a  little  undis- 
solved  caseine  behind. 

Paste  for  scrapbooks.  Rice  starch  1  oz.,  gelatine  3 
drachms,  water  J  pint. 


PREPARATION  OF  CEMENTS,   PASTES,  AND  MUCILAGES.       267 

Heat,  stirring  constantly,  until  the  milky  fluid  becomes 
thick  and  gluey.  When  the  paste  is  nearly  thick  put  in  a 
bottle  closely  corked.  It  is  well  to  add  a  few  drops  of  oil 
of  cloves  to  each  bottle. 

Paste  for  skins.  Pour  enough  boiling  water  over  1  Ib.  of 
rye  flour  in  a  basin  to  make  a  stiff  paste,  almost  as  stiff  as 
ordinary  dough  for  puddings.  Stir  and  beat  up  well  with 
a  stick  for  three  or  four  minutes,  then  cover  up  and  let  it 
stand  for  two  days  before  using,  when  it  will  be  much  softer 
and  stick  better.  Spread  thinly  and  evenly  on  the  back  of 
the  skin  with  a  stiff  brush  or  pad.  It  will  stick  firmly  and 
not  crack. 

Strong  mucilage  capable  of  fastening  wood  or  china  and 
glass  together  is  made  of  3J  ozs.  of  strong  gum  arabic  solu- 
tion, to  which  a  solution  of  30  grains  of  sulphate  of  alumin- 
ium dissolved  in  f  oz.  of  water  is  added. 

Dextrine  mucilage.  I.  Dissolve  with  the  assistance  of  heat 
60  parts  of  borax  in  420  parts  of  water,  add  480  parts  of 
pale  yellow  dextrine  and  50  parts  of  glucose,  and  heat  care- 
fully, stirring  constantly  until  solution  is  complete,  replac- 
ing the  water  lost  by  evaporation.  Strain  through  flannel. 

The  resulting  mucilage  is  quite  clear,  has  great  adhesive 
power,  arid  dries  very  quickly.  In  heating  the  mixture, 
great  care  should  be  exercised  not  to  exceed  a  temperature 
of  194°  F.  and  not  to  heat  too  long,  otherwise  the  product 
readily  becomes  brown  and  brittle. 

II.  Dextrine  120  parts,  powdered  alum  6,  sugar  30,  car- 
bolic acid  1,  distilled  water  300.  Gradually  mix  the  dex- 
trine, alum  and  sugar  with  the  water,  effect  solution  by 
boiling  and  when  the  solution  is  cold,  add  the  carbolic  acid. 

Paste  for  joining  leather  to  pasteboard.  Dissolve  50  parts 
of  strong  glue  with  a  little  water  at  a  gentle  heat,  then  add 
a  small  quantity  of  Venice  turpentine,  and  next  a  thick 
paste  made  with  100  parts  of  starch  in  water.  Apply 
quickly  when  cold. 

Another  formula  for  a  similar  paste  is  as  follows:  Rye 


268  GLUE,    GELATINE,    CEMENTS,    PASTES. 

whisky  2  pints,  water  1  pint,  powdered  starch  4J  ozs.,  good 
glue  1J  ozs.,  Venice  turpentine  1J  ozs.  Mix  the  whisky 
and  water  together,  then  stir  in  the  starch  and  make  a  thick 
paste.  Separately  dissolve  the  glue  in  an  equal  weight  of 
water,  and  mix  the  Venice  turpentine  therein,  mix  thor- 
oughly, and  then  compound  this  mixture  with  the  thick 
paste  by  constantly  stirring  until  all  is  well  incorporated. 

Paste  for  attaching  labels  to  polished  nickel.  Dissolve  400 
parts  by  weight  of  dextrine  in  600  parts  of  water,  and  add 
20  parts  of  glycerine  and  10  parts  of  glucose.  Heat  the 
mixture  to  194°  F. 

Another  formula  is  as  follows :  Mix  400  parts  by  weight 
of  dextrine  with  water,  and  add  200  parts  of  water  together 
with  20  parts  of  glucose  and  10  parts  of  aluminium  sulphate. 

Mucilage  for  attaching  labels  to  tin.  I.  Shellac  8  parts, 
borax  4  parts,  water  60  parts.  Boil  until  the  shellac  is 
dissolved. 

II.  To  2  parts  of  dammar  varnish  add  8  parts  of  traga- 
canth  mucilage. 

III.  An  excellent  mucilage  for  the  purpose  consists  of 
starch  paste  to  which  a  small  quantity  of  Venice  turpentine 
has  been  added. 

IV.  Make  a  paste  of  corrosive  sublimate  2J  parts,  wheat 
flour  200,  absinthe  100,  tansy  50,  water  3000.     This  muci- 
lage is  useful  for  vessels  kept  in  a  damp  place. 

Mucilage  for  office  use.  Gum  arabic  100  parts,  aluminium 
sulphate  6  parts,  glycerine  10,  dilute  acetic  acid  20,  distilled 
water  140.  Dissolve,  in  a  wide-mouthed  glass  bottle,  the 
gum  arabic  in  cold  distilled  water,  stirring  frequently.  Let 
the  solution  stand  2  or  3  days,  then  add  the  glycerine,  later 
on  the  dilute  acetic  acid  and  finally  the  aluminium  sul- 
phate. Strain  through  a  hair  sieve,  allow  to  clarify,  and 
decant  from  the  sediment. 

Glycerine  paste  for  office  use.  Dissolve  4  ozs.  of  gurn  arabic 
and  8  drachms  of  glycerine  in  12  ozs.  of  boiling  water. 

Clean  and  durable  paste.     Dissolve  5  ozs.  of  gum  arabic  in 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       269 

4  quarts  of  warm  water,  and  thicken  to  a  paste  with  wheat 
flour.  Then  add  a  solution  of  alum  and  sugar  of  lead, 
3  ozs.  of  each  in  water.  Heat  the  mixture  and  stir  it  until 
it  is  about  to  boil,  and  then  cool  it.  If  too  thick,  add  gum 
solution. 

Banknote  or  mouth  glue.  Dissolve  by  the  aid  of  heat  a 
fine  quality  of  glue  or  gelatine  with  about  a  quarter  or  one- 
third  of  its  weight  of  brown  sugar,  in  as  small  a  quantity  of 
water  as  possible.  Then  when  perfectly  liquid  cast  the 
mixture  into  thin  cakes  on  a  flat  surface  very  slightly  oiled, 
and  when  cold  cut  up  into  pieces  of  convenient  size.  When 
required  for  use  moisten  one  end.  A  piece  of  this  glue 
kept  in  the  desk  will  be  found  very  convenient  for  many 
purposes. 

Paste  for  cardboard.  Dissolve  3J  ozs.  of  best  French  glue 
in  6J  ozs.  of  water  by  soaking  and  heating.  Then  add  a 
solution  of  J  drachm  of  shellac  in  3J  drachms  of  alcohol 
and  stir  as  long  as  the  solution  is  warm.  Next  dissolve  2 
drachms  of  dextrine  in  If  ozs.  of  alcohol  and  14  drachms 
of  water,  stir,  and  place  the  vessel  in  warm  water  until  solu- 
tion is  complete.  Mix  this  solution  with  that  of  the  glue, 
and  pour  the  whole  into  a  suitable  vessel,  in  which  it  may 
solidify.  When  wanted  for  use  cut  off  a  small  piece  and 
liquefy  it  by  warming. 

Paste  for  attaching  cloth  or  leather  to  table  tops.  Wheat 
flour  1  lb.,  powdered  rosin  2  tablespoonfuls,  powdered  alum 
1  tablespoonful.  Heat  and  stir  to  a  stiff  consistency. 

Caseine  mucilage.  Separate  the  caseine  from  milk  with  a 
little  tartaric  acid,  and  treat  the  caseine  while  still  warm 
with  a  solution  of  6  parts  borax  to  100  parts  water  and  warm 
gently  while  stirring,  which  will  cause  the  caseine  to  be  dis- 
solved. Of  the  borax  solution  enough  should  be  used  to 
leave  only  a  little  undissolved  caseine  behind. 

Very  adhesive  paste  which  may  be  used  for  wood  and  parch- 
ment. Gum  arabic  60  parts,  fine  wheat  starch  45,  sugar  15. 
Dissolve  the  gum  ifn  as  much  water  as  is  required  for  boil- 

• 


270  GLUE,    GELATINE,    CEMENTS,    PASTES. 

ing  the  quantity  of  paste  to  be  made.  Then  add  the  starch 
and  sugar  and  boil  it  in  a  vessel  suspended  in  boiling  water 
until  the  mixture  is  clear  and  has  the  consistency  of  liquid 
tar.  Keep  in  a  well-closed  vessel  protected  from  mould  by 
the  addition  of  a  few  drops  of  oil  of  cloves. 

Paste  for  pads.  Glue  4  parts  by  WT eight,  glycerine  2,  lin- 
seed oil  J,  sugar  4,  aniline  dye  sufficient  to  color.  Soften 
the  glue  by  soaking  in  cold  water,  then  dissolve  together 
with  the  sugar  in  the  glycerine  by  the  aid  of  heat  over  the 
water-bath,  then  add  the  dye  and  stir  in  the  oil.  Use  the 
paste  hot. 

Paste  for  fastening  paper  on  tin-foil.  Make  a  paste  by  dis- 
solving rye  flour  in  a  solution  of  caustic  soda  ;  dilute  with 
water,  stirring  constantly.  Add  to  this  paste  a  few  drops 
of  Venice  turpentine  for  each  J  Ib.  flour  used.  This  paste 
adheres  to  all  kinds  of  metal,  tin-foil,  glass,  etc. 

Paste  for  attaching  labels  to  glass,  porcelain,  and  metal. 
Gum  arabic  15  parts,  pulverized  tragacanth,  7J,  glycerin 
45,  thymol,  0.3,  alcohol  3f ,  water  120.  Dissolve  the  gum 
arabic  in  15  parts  of  water  and  triturate  the  tragacanth 
with  30  parts  of  water.  Mix  the  two  fluids  and  strain. 
Then  add  the  glycerine  and  finally  the  thymol  dissolved  in 
the  alcohol. 

Preparation  of  arabol-gum.  Mix  intimately  44  Ibs.  of 
wheat  starch  with  176  Ibs.  of  water.  Bring  the  mass  into 
a  water-bath,  mix  it  with  a  solution  of  4.4  Ibs.  of  oxalic 
acid  in  44  Ibs.  of  water  and  heat  for  four  hours  at  194°  F., 
stirring  frequently.  The  conversion  of  the  starch  is  as  a 
rule  effected  during  this  time,  but  should  such  not  be  the 
case,  continue  heating,  constantly  replacing  the  evaporated 
water,  until  the  mass  is  clear  and  liquid.  While  still  hot, 
neutralize  the  mass  with  marble  dust,  allow  to  settle,  filter, 
and  evaporate  the  clear  solution  in  a  water-bath  to  a  solid 
gum  containing  about  15  per  cent,  of  water. 

Preparation  of  an  adhesive  substance  from  desaccharized  beet- 
root slices  (German  patent  96316  f.  G.  Eichelbaum).  The 


PREPARATION  OF  CEMENTS,  PASTES,  AND  MUCILAGES.       271 

insoluble  metarabin  contained  in  the  slices  is  converted 
into  soluble  arabin  by  treating  the  slices  under  pressure 
with  hot  aqueous  sulphurous  acid  or  with  aqueous  solutions 
of  the  bisulphites  of  the  alkalies  or  alkaline  earths. 

According  to  a  later  patent  (German  patent  121422  f. 
Fabrik  Bettenhausen  Marquart  and  Schulz),  the  insoluble 
metarabin  is  converted  into  soluble  arabin  by  heating  the 
desaccharized  beet-root  slices  with  phosphoric  acid  and 
water.  According  to  a  supplement  to  this  patent  (122048), 
conversion  is  effected  by  heating  the  slices  with  aqueous 
solutions  of  organic  acids  and  phenols,  or  the  acid  salts  of 
oxalic,  tartaric  or  phosphoric  acids. 


INDEX. 


ACID  calcium  phosphate,  120 
crystallization   of, 

125,  126 
formation  of,  121- 

124 
sodium  sulphate,  use  of,  in  drying 

glue,  72,  73 
Acidity,  determination  of,  in  glue,  205, 

206 

Acids,  dilute,  effect  of,  on  glue  solu- 
tion, 7 

Adamson,  Wm.,  method  of,  for  remov- 
ing hydrocarbons  from 
substances  which  have 
been  treated  therewith, 
84-86 

method    of,    for  treating 
substances  with  hydro 
carbon   vapor   for   the 
purpose  of  extracting 
oils,  fats,  etc.,  79-82 
method   of,  for   treating 
substances  with  liquid 
hydrocarbons    for    the 
purpose  of  extracting 
oils,  fats,  etc.,  82-84 
and  Simonis,  Chas.  F.  A., 
apparatus    of,  for   ex- 
tracting    bones    with 
benzine,  76-79 
Adhesive  paste,  264 
Adulterations   of  glue,  determination 

of,  214,  215 

Agur-Agar,   12,  201,  202 
Air-bladders,  16,  41 

bleaching  glue  in  the,  141 
drying  the  cakes  of  glue  in  the, 

64 
Alabaster,  244 

cement  for,  242 
Albumen  paste,  265,  266 

use  of,  for  clarifying  glue  liquor,  54 
Alum  cement,  228 

effect  of,  on  glue  solution,  7 

use  of,  for  clarifying  glue  liquor,  54 

preserving  paste,  257 
Amber,  resinous  cement  for,  229 
American  cement  for  jewelers,  252 


American  glue,  analysis  of,  207 
Ammonium  sulphate,  use  of,  in  drying 

glue,  72,  73 
Animal  charcoal,  bleaching  glue  with, 

142 
bones  for  the  manufacture 

of,  107 
carbonization  of  bones  for, 

108-112 
decolorizing     glue     liquor 

with,   55 

manufacture  of,  112,  113 
yield  of,  113 

skin,  constitution  of,  17,  18 
Antiseptics    for    the    preservation    of 

glue-stock,  30 
Arabin,  conversion  of  metarabin  into, 

271 

Arabol-gum,  preparation  of,  270 
Ash,  burning  bones  to,  117-119 

BACTERIOLOGY,  use  of  gelatine  in, 
194 

Banknote  glue,  269 
Barium    chloride,    effect    of,    on    glue 

solution,  7 

Basic  calcium  phosphate,  120 
Beet-root  slices,  desaccharized,  prep- 
aration  of    an    adhesive  substance 
from,  270,  271 

Belgian    retort-furnace    for    the    car- 
bonization of  bones,  109-112 
Benzine,    extracting    fat    from    bones 

with,  76-92 

Billiard  balls,  compound  for,  155,  156 
Bleaching  glue,  methods  of,  141-145 

stock,  55,  56 
Blood,  fresh,  use  of,  for  clarifying  glue 

liquor,  54 

Blumenthal's  method  of  preparing  dex- 
trine, 260,  261 
Boiler  for  glue  boiling,  44 
Boiling  bones,  74,  75 
duration  of,  45 
or  cooking  glue,  44-52 
Bone  ash,  composition  of,  119 

conversion  of,  into  a  coarse 
powder,  119 


18 


(273) 


274 


INDEX. 


Bone  ash,  decomposition   of,  by   sul- 
phuric acid,  119-125 
kiln  for,  117-119 
preparation  of,  117-119 
yield  of,  119 

cartilage,  composition  of,  32 
cement  for,  230 
crusher,  36 
gelatine,  170-180 

modern  process  of  preparing, 

179,  180 

-glue,  manufacture  of,  74-116 
meal,  glue  and  fat,  simultaneous 
utilization  of  bones  for,  1 04-1 1 3 
-mill,  Crosskill,  36 
raw  materials,  16 
size,  159,  160 
Bones,  absorption  of  sulphurous  acid 

by,  92 
Adamson  and  Simonis'  apparatus 

for  extracting,  76-79 
and  cartilages,  31-39 
apparatus  for  extracting  the  fat 

from,  with  benzine,  76-94 
Belgian  retort-furnace  for  the  car- 
bonization of,  109-112 
boiling  of,  74,  75 
burning  of,  to  ash,  117-119 
buying  of,  32 
carbonization  of,  108-112 
constitution  of,  32 
crushed,  sorting  of,  36,  37 
crushing  or  grinding  of,  33-36 
extraction  of,  76-94 

phosphates  from,115 
fatty  matters  in,  32 
for    the    manufacture    of    animal 

charcoal,  107 
honey-combed,  39 
Leuner's  apparatus  for  extracting, 

90-92 

lime  bath  for,  37 

products  obtained  in  the  distilla- 
tion of,  112 

Seltsam's  apparatus  for  extract- 
ing, 84-86 

apparatus  for  extracting,  im- 
proved by  Th.  Richter,  88- 
90 

simultaneous  utilization  of,  for 
fat,  bone-meal  and  glue, 
104-113 

utilization  of,  for  fat,  glue  and 
calcium  phosphate,  113- 
116 

sorting  of,  32,  33,  104,  105 
sulphurous   acid    for    extracting, 
92-94 


Bones,  treatment  of,  with  high  pressure 

steam,  105-107 

utilization  of  the  liquor  obtained 
in  the  treatment  of,  with  hydro- 
chloric acid,  125-127 
value  of,  32 
waste  of,  from  the  preparation  of 

tinned  provisions,  19 
Bookbinder's  glue,  12 

size,  160 

Book  isinglass,  197 
Boric  acid,  preservation  of  glue-stock 

with,  30 

Bottles,  cracked,  cement  for,  240,  241 
Bouillon  tablets,  12 
Brazilian  isinglass,  199,  200 
Briers,  D.  J.,  prcrcess  for  the  prepara- 
tion of  bone  gelatine  employed  by, 
171-179 
Brochette,  43 
Brushmaker's  cement,  251 
Bullock's  feet,  18 

hide,  waste  of,  18 
leather,  30 
Burning  bones  to  ash,  117-119 

/^AKES,  cutting  glue  into,  57-64 
\J        drying  the,  64-73 

machines  for  cutting  the  jelly 

into,  60-64 
shape  of,  57,  58 
tools  for  cutting  the  jelly  into, 

59 
Calcium  chloride,  116 

metaphosphate,  120,  127 
phosphate,  115 

fat    and    glue,   simultaneous 
utilization    of    bones    for, 
113-116 
Calf  leather,  30 

skin  waste,  18 
Calves'  feet,  30 

heads,  18,  30 

Carbolic  acid,   preservation    of   glue- 
stock  with,  29 
use    of,    for    preserving 

paste,  257,  258 

Carbon  disulphide,  use  of,  for  extract- 
ing bones,  76 
Cardboard,  paste  for,  269 
Cartilage,  1 

conversion  of,  into  glue,  94-104 

drying  of,  114 

preservation  of,  114 

treatment  of,  with  high-pressure 

steam,  98 

yield  of  glue  from,  115 
Cartilages  and  bones,  31-39 


INDEX. 


275 


Caseine  cement  which  can  be  kept  for 

a  long  time,  239 
cements,  237-240 
mucilage,  264 

for  photographer's  use,  266 
ordinary  technical,  preparation  of, 

238,  239 

pure,  preparation  of,  23V,  238 
Castings,  cement  for  filling  in  defects 

in,  246 
Cattle,  pieces  of  hide  from  the  lower 

parts  of  the  limbs  of,  30 
Cayenne  isinglass,  199,  200 
Cellular  tissue,  1 
Celluloid,  cement  for,  252 
Cement  resisting  acids,  248 

very  high  temperatures,  248 
Cements,  caseine,  237-240 
chemical  nature  of,  219 
classification  of,  218-223 
for  chemical  apparatus,  247-249 

special  purposes,  249-252 
glue  and  starch,  222,  223 
glycerine,  242 
gypsum,  244,  245 
how  to  use,  252-255 
iron,  245-247 
lime,  223,  243,  244 
oil,  219,  220,  224-229 
pastes  and  mucilages,  preparation 

of,  224-271 

resinous,  220,  221,  229-233 
resisting  high  temperatures,  246 
rubber  and  gutta-percha,  222, 233- 

237 

water  glass,  240-242 
Chalk,  243 
Charcoal,  animal,  bleaching  glue  with, 

142 

bones  for  the  manufac- 
ture of,  107 
carbonization    of    bones 

for,  108-112 

manufacture  of,  112,  113 
yield  of,  113 
mixing   calcium  phosphate  with, 

124 
Chemical  apparatus,  cements  for,  247- 

249 

Chinese  isinglass,  201,  202 
Chlorbarium,  soaking  hides  in,  20 
Chloride  of  \irne,  bleaching  glue- stock 

with,  55 

Chlorine,  bleaching  glue  with,  141 
Chondrin,    chemical    composition    of, 

5,6 

conversion  of,  into  glutin,  6 
formation  of,  3 


Chondrin,  properties  of,  5 

pure,  preparation  of,  5 
Chrome  glue,  153 
Clarifying  glue  liquor,  52-56 

apparatus  for,  98 
vats,  53 
Clay   crucibles,   cracked,  cement   for, 

243 

Clearness  of  glue,  definition  of,  53 
Clock  faces,  white  enameled,  cement 

for,  230 
Cloth,  cement  for,  252 

paste  for  attaching,  to  table  tops, 

269 

Colle  franche,  43 
Cologne  glue,  148 
Color  mixtures,  glue  for,  11 
of  glue,  definition  of,  53 
Colored  gelatine,  181,  182 
Coloring  glue,  156 

matters  for  gelatine,  181,  182 
substances,  removal  of,  from  glue 

liquor,  54-56 

Combs,  hard  rubber,  cement  for,  236 
Common  salt,  effect  of,  on  glue  solu- 
tion, 7 

Constitution  of  glue,  3-6 
Conversion  of  cartilage  into  glue,  94- 

104 
Cooking,  duration  of,  44 

or  boiling  glue,  44-52 
Cooling  boxes,  100 

glue  liquor,  100 
Corium,  1.  17 
Court-plaster,  12,  184,  185 
Cox,  J.  and  G.,  process  for  the  manu- 
facture of  gelatine  patented  by,  166, 
167 

Crockery,  cement  for,  236,  237 
Crosskill  bone  mill,  36 
Crucibles,  cement  for,  243 
Crude  glue,  definition  of,  3 
preparation  of,  43 
Culinary  purposes,  glue  for,  12-14 

T\ARK  steam  glue,  152 
J-/     Devoulx,    cutting    apparatus    in- 
vented by,  62-64 
Dextrine  mucilage,  267 

preparation  of,  259-261 
Diamond  cement,  229 
Distillation  of  crude  phosphorus,  133- 

135 

phosphorus,  127-132 
Drying,  acceleration  of,  72,  73 
cakes  of  glue,  64-73 
galleries,  68-71 
house,  modern,  71,  72 


276 


INDEX. 


Drying  room,  65 

regulating  the  temperature  of 
the,  67,  68 

EAST  INDIA  isinglass,  199 
Elastic  cement,  234 

gutta-percha  cement,  236 
masses,  glue  for,  14 
paste,  263 
Electric  furnace  for  the  manufacture 

of  phosphorus,  138-140 
Electrical  apparatus,  cement  for,  251, 

252 

Emery  paper,  use  of  glue  in  the  manu- 
facture of,  12 
Epidermis,  17 
Epsom  salt,  behavior  of  glue  solution 

towards,  7 

use  of,  in  drying  glue,  72,  73 
Evaporating  pan,  open,  98-100 

pans,  124 

Evaporators,  spiral,  100,  101 
Extraction  of  bones,  76-94 

FABRICS,   water-proofing    of,    161- 
163 

Fancy  articles,  fine,  paste  for,  265 
Fans,  gelatine  veneers  for,  15 
Fat,  bone  meal  and  glue,  simultaneous 
utilization    of  bones   for,    104- 
113 

extraction  of,  with  benzine,  76-92 
hydrocarbon     va- 
pors, 79-82 
liquid     hydrocar- 
bons, 82-84 

glue     and      calcium     phosphate, 
simultaneous       utilization      of 
bones  for,  113-116 
Fertilizers,  utilization   of  liquors  for, 

116 

Fining,  gelatine  for,  182 
Fish  bladders,  1 
glue,  202-204 

points  to  be  observed  in  the 

manufacture  of,  41,  42 
raw  materials  for,  41,  42 
scales,  16,  42 

preparation  of  glue  from,  203 
Fleck's    kiln  for  burning   bones,  118, 

119 
process  of  accelerating  the  drying 

of  glue,  72,  73 

Flour  paste,  256-258,  261,  262 
Fluid  pastes,  264,  265 
Foils,  gelatine,  15,  185,  186 
Formaldehyde,    preservation    of  glue- 
stock  with,  29,  30 


Forming  or  moulding  the  glue,  56-64 
Formo-gelatine,  193,  194 
French  mastic,  227 

putty,  225 

Friedberg's  apparatus  for  clarifying 
glue  liquor, 
98 

conversion  of 
car  t  i  lage 
into  glue, 
94-97 

Furnace,  electric,  for  the  manufacture 
of  phosphorus,  138-140 

pALLEY  furnace,  128,  129 
VT     Galvanized  iron-wire  netting,  66 
Gelatin,  pure,  preparation  of,  4 
Gelatine  and  glycerine,  compound  of,  12 
and   products   prepared    from    it, 

manufacture  of,  165-195 
artificial  silk  from,  195 
capsules,  14,  184 
colored,  181,  182 
constitution  of,  165 
Cox:s  process  for  the  manufacture 

of,  166,  167 
foils,  15,  185,  186 
for  fining  purposes,  182 
for     photographic     printing    and 
photographic  purposes  in  gen- 
eral, 183,  184 
Jullion  and  Pirie's  process  for  the 

preparation  of,  38 
Nelson's  process  for  the  manufac- 
ture of,  166 
preparation     of,     from     ordinary 

glue,  182,  183 
substitute  for,  203,  204 
Swinborne's    improved     patented 
process  for  the  preparation  of, 
167 

testing  of,  205-217 
veneers,  15,  186-193 
yielding  tissues,  1 
German  isinglass,  200 
Gilder's  glue,  150 
Glass,  cement  for,  230,  233,  239,  241, 

243,  245 
for  attaching  metal  letters 

to,  249 
to  metal,  251 
mastic  cement  for,  232 
oil  cement  for,  228 
paper,  use  of  glue  in  the  manufac- 
ture of,  1 2 

paste  for  attaching  labels  to,  270 
plates,  gelatinizing  liquors  upon, 
58,  59 


INDEX. 


277 


Glass  upon  glass,  cement  for,  230 

metal,  cement  for,  230 
Glauber's  salt,  use  of,  in  drying  glue, 

72,  73 
Gloves,  waste    from   the  manufacture 

of,  43 
Glue,   acceleration   of  the   drying  of, 

72,  73 
addition  of  mineral  substances  to, 

149 

American,  analysis  of,  207 
and  starch  cements,  222,  223 
as  a  binding  agent,  11 

joining  medium,  10,  11 
banknote  or  mouth,  2G9 
boiler,  Terne's,  51,  52 
boiling,  boiler  for,  44 

convenient  apparatus  for,  46, 

47 

in  open  jacketed  pans,  49,  50 
or  cooking,  44-52 
with  steam,  boiler  for,  47-49 
chemical  composition  of,  8 
chrome,  153 
clearness  of,  53 
Cologne,  148 
color  of,  53 
coloring  of,  156 
constitution  of,  3-6 
conversion  of  cartilage   into,  94- 

104 

cooking,  process  of,  51 
crude,  definition  of,  3 

preparation  of,  43 
cutting  the,  into  cakes,  57-64 
deduction  of  the  quality  of,  from 

indirect  properties,  207,  208 
determination  of  acidity  in,  205, 

206 

of  adulterations  of,  214,  215 
of  glutin  in,  206,  207 
of  moisture  in,  205 
different   varieties   of,    and   their 

preparation,  146-164 
drying  cakes  of,  64-73 

room  for,  65 
factory,  location  of  a,  21 

manner  of  carrying   on   the 

work  in  a,  26-30 

fat  and  bone-meal,  simultaneous 
utilization  of  bones  for,  104- 
113 

for  attaching  leather  to  metal,  153 
culinary    and    medicinal   pur- 
poses, 12-14 
elastic  masses  and  as  a  partial 

substitute  for  rubber,  14 
fancy  articles,  14,  15 


Glue  joints  in    leather   driving   belts, 

163 

leather,  paper,  etc.,  153,  154 
parchment    paper   in    making 

sausage  skins,  154,  155 
formation  of,  6 
from    various    materials,  external 

characteristics  of,  6,  7 
gilder's,  150 

holding  power  of,  147,  148 
how  to  make  and  use,  147 
in  animal  organism,  2 

sizing,  12 

inferior  qualities  of,  12 
joiner's,  146 

Kissling's  results  in  testing,  215 
liquid,  151,  152 

liquor,  apparatus  for  clarifying,  98 
clarifying  the,  52-56 
concentration  of,  50 
cooling  of,  100 
decolorizing  of,  with  animal 

charcoal,  55 
instrument  for  measuring  the 

percentage  of  glue  in,  103 
measuring   the   percentage   of,  in 

glue  liquor,  103,  104 
methods  of  bleaching,  141-145 
moulding  or  forming  of,  56-64 
nature  of,  1-9 
nets  for  drying,  66,  67 
ordinary,  preparation  of  gelatine 

from,  182,183 
parchment,  150 
Paris,  150,  151 
patent,  150 

practical  testing  of,  215-217 
principal  substances  employed  as 

raw  material  for,  16 
properties  of,  and  its  behavior  to- 
wards other  substances,  6-9 
raw  materials  and  their  prepara- 
tion  for    the    manufacture   of, 
16-38 

results  obtained   by  comparative 
experiments  in  testing,  209,  210 
Russian,   149,  150 
size,  150 
solution,    behavior     of,    towards 

salts,  7,  8 
steam,  152 

stock,  bleaching  of,  55,  56 
dry-limed,  19 
dry,  uncured,  or  salted,  19 
green-limed,  19 
green-salted,  19 
influence  of  the  age  of  animals 
on  the  product  from,  20 


278 


INDEX. 


Glue  stock,  limed,  washing  of,  21-26 
notes  in  reference  to  judging, 

19,  20 

preparation  of,  21-38 
preservation  ot,  29 
sheds  for,  26 
transformation      in     boiling 

the,  2 

washer,  22-26 
substitute  for,  203,  204 
transition  stages  of,  2 
uses  of,  10-15 
testing  of,  205-217 
tungstic,  155 
water-proof,  160 
yield  of,  from  cartilage,  115 

from  tannery  waste,  18 
-yielding    substance,     production 

of,  2 

tissues,  1 

Glutin,  conversion  of  chondrin  into,  6 
determination  of,  in  glue,  206,  207 
formation  of,  3 
properties  of,  4,  5 
pure,  preparation  of,  4 
Glycerine  and  glycerine  cements,  242 

litharge  cement,  242 
paste,  266 

for  office  use,  268 
properties  of,  242 
Glycocoll,  6 
Goat  leather,  31 
Gray  lime,  28 

Green  waste,  liming  of,  26,  27 
Gum  tragacanth,  261 
Gutta-percha  and  rubber  cements,  222, 

233-237 
Gypsum,  244 
Gypsum  cements,  244,  245 

HAGER'S  diamond  cement,  229 
Hard  rubber  cement,  234 

combs,  cement  for,  236 
Hare  skins,  18,  31 
Hartshorn,  1 
Hayes,  S.  Dana,  analysis  of  American 

glue  by,  207 

Heat-resisting  cement,  245 
Hectograph  mass,  14,  163,  164 
Heuz6's  method  of  preparing  dextrine, 

261 

Hide,  transformation  in  drying  the,  2 
Hides  for  glue-stock,  classification  of, 

30,   31 

soaking  of,  in  chlorbarium,  20 
Hoeveller,  W.  A.,  apparatus  for  drying 
glue  invented  by,  68- 
71 


Hoeveller,  W.  A.,   glue-stock  washer 

of,  22-26 
Hog  skins,  18 
Hollander,  39 
Horn,  cement  for,  232 

piths,  19 

Horses'  hoofs,  cement  for,  236 
Hudson  Bay  isinglass,  199 
Hydraulic  works,  cement  for,  241 
Hydrocarbon  vapors,  extraction  of  fats, 

oils,  etc.,  with,  79-82 
Hydrocarbons,    liquid,    extraction    of 

fats,  oils,  etc.,  with,  82-84 
removal  of,  from  substances,  84-86 
Hydrochloric  acid,  treatment  of  bones 

with,  37 

utilization  of  the  liquor 
obtained  in  treating 
bones  with,  125-127 

ICHTHYOCOLLE     Frangaise,     200, 
201 

Irish  moss,  202 

Iron  and  stone,  cement  for,  245 
cement  for,  245,  246 
cements,  245-247 
pipes,  fire-proof  cement  for,  246 
pots,  cracked,  cement  for,  246 
water  tanks,  cement  for,  246 

Isinglass,  adulteration  of,  196,  197 
and  its  substitutes,  196-204 
chemical  composition  of,  8 
preparation  of,  in  Russia,  197,  198 
sources  of,  196 
spurious,  196 
substitute  for,  203,  204 

Isinglassine,  201 

Ivory,  cement  for,  230 

JEFFREY'S  marine  glue,  235 
*)     Jelly,  definition  of,  3 

effect  of  tannin  on,  8 
machines  for  cutting  the,  into 

cakes,  60-64 
properties  of,  7 
tools  for  cutting  the,  into 

cakes,  59 
transformation    in    boiling 

the,  2 
Jennings'  method  for  the  preparation 

offish  glue,  202,  203 
Jewelers,  American  cement  for,  252 

cement,  252 
Joiners,  cement  for,  243 

glue,  146 

Jullion   and    Pirie's   process    for    the 
preparation  of  gelatine,  38 


INDEX. 


279 


KID  leather,  waste  from  paring,  31 
Kiln  for  burning  bones,  117-119 
Kissling's  results  in  testing  glue,  215 
Knapsack  leather,  31 
Knife  handles,  cement  for,  231 

LABEL  paste,  263 
Labels,  mucilage  for,  263 

paste  for  attaching,  to  glass, 
porcelain    and    metal, 
270 
for  attaching,  to  polished 

nickel,  268 

for  attaching,  to  tin,  268 
Lamb  leather,  31 
Leaf  isinglass,  197 
Leather,  cement  for,  235,  237 

driving  belts,  glue  for  joints  in,  163 
for  glue-stock,  classification  of,  30 

31 
glue  for,  153,  154 

attaching,  to  metal,  153 
paste  for  attaching,  to  table  tops, 

269 
joining,    to    pasteboard, 

267,  268 

skins,  actual,  17 
waste,  39-42 

comminution  of,  39,  40 
Leucine,  6 
Leuner's     apparatus     for     extracting 

bones,  90-92 
Lime  and  glue  cement,  244 

sugar  paste,  265 
bath  for  bones,  37 
cements,  223,  243,  244 
milk  of,  preparation  of,  26,  27 
precipitation  of,  by  oxalic  acid,  54 
slaked,  effect  of,  on  glue  solution, 7 
testing  of,  27,  28 

Limed  glue-stock,  washing  of,  21-26 
Liming  green  waste,  26,  27 

waste,  20 
Linseed  oil  and  clay  cement,  248 

manganese  cement,  248 
Lipowitz's  method  of  testing  glue,  208, 

209 

Liquid  fining  gelatine,  182 
glue,  151,  152 
sugar  and  lime  paste,  265 
Litharge  cement,  225 

MAGNESIUM  sulphate,  116 
Manufacture   of  bone-glue,   74- 

116 

of  gelatine,  and  products 
prepared  from  it,  165- 
195 


Manufacture  of  phosphorus,  117-140 

skin  glue,  43-73 
Maps,  paste  for  mounting,  266 
Marble,  cement  for,  242,  251 

for  attaching  metal  letters 

to,  249 

oil  cement  for,  228,  229 
Marine  glue,  234,  235 
Matches,  use  of  glue  in  the  manufac- 
ture of,  11 
Mastic,  226,  227 

cement,  226,  227 

Medicinal  purposes,  glue  for,  12-14 
Meerschaum,  cement  for,  239 
Meta-gelatin,  7 
Metal,    cement    for    attaching    wood, 

glass,  etc.,  to,  251 
glue  for  attaching  leather  to,  153 
letters  upon  glass,  cement  for,  230, 

249 

paste  for  attaching  labels  to,  270 
Metals,  cement  for,  239 

for  uniting,  241 
Metarabin,  conversion  of,  into  arabin, 

271 

Mica,  cement  for,  231,  232 
Milk  of  lime,  preparation  of,  26,  27 
Moisture,    determination   of,   in    glue, 

205 

Mother-of-pearl,  glue  imitations  of,  15 
Moulding  boxes,  56 

or  forming  the  glue,  56-64 
refined  phosphorus,  135-137 
Mouth  glue,  269 
Mucilage,  263,  264 
caseine,  264 

for  photographers'  use,  266 
dextrine,  267 

for  attaching  labels  to  tin,  268 
labels,  263 
office  use,  268 
postage  stamps,  264 
preservation  of,  259,  260 
strong,  267 
tragacanth,  264 
Mucilages  and  pastes,  255-271 

for  special  purposes, 

261-271 
pastes   and   cements,   preparation 

of,  224-271 
Muratori    and    Landry's     method    of 

water-proofing  fabrics,  162,  163 
Muzmann  and   Krakowitzer's  method 
of  water-proofing  fabrics,  162,  163 

NATURE  of  glue,  1-9 
Nelson,    G.,   process   of,   for   the 
manufacture  of  gelatine,  166 


280 


INDEX. 


Nets  for  drying  glue,  66,  67 
Netting,  metallic,  66 

twine,  66,  67 
Neutral  potassium    tartrate,  behavior 

of  glue  solution  towards,  7 
New  York  isinglass,  198 
Nickel,    polished,  paste  for  attaching 

labels  to,  268 
North  American  isinglass,  198 

OFFICE  use,  glycerine  paste  for,  268 
mucilage  for,  268 
Oil  cements,  219,  220,  224-229 
Oils,  extraction  of,  with  hydrocarbon 

vapors,  79-82 
with  liquid  hydro- 
carbons, 82-84 

Ornaments,  indestructible  mass  for,  155 
Osseine,  1 

Oxalic  acid,  effect  of,  on  glue  solution,  7 
precipitation  of  lime  by,  54 

PADS,  paste  for,  270 
Paget's  mastic,  227 
Pale  steam  glue,  152 
Pan,  open  evaporating,  98-100 
Pans,  evaporating,  124 
open  jacketed,  49,  50 
vacuum,  101-103 
Paper  bags,  paste  for,  266 

colored,  use  of  glue  in  the  manu- 
facture of,  1 1 
glue  for,  153,  154 
hangings,  glue    in    the    manufac- 
ture of,  11 
paste  for,  265 

fastening,     on      tin-foil, 

266,  270 
Parchment  glue,  150 

paper,  glue  for,  in  making  sausage 

skins,  154,  155 
scraps,  18 

Paris  glue,  150,  151 
Paste,  adhesive,  264 
albumen,  265,  266 
clean  and  durable,  268,  269 
elastic  or  pliable,  263 
fluid,  264,  265 
for  attaching  cloth  or  leather  to 

table  tops,  269 
labels  to  glass,  porcelain 

and  metal,  270 
to  polished  nickel,  268 
cardboard,  269 
fastening   paper  on   tin    foil, 

266,  270 

joining  leather  to  pasteboard, 

267,  268 


Paste  for  mounting  maps,  266 
pads,  270 
paper  and  fine  fancy  articles, 

265 

bags,  266 

scrap-books,  266,  267 
skins,  267 
glycerine,  266 

for  office  use,  268 
label,  263 

preparation  of,  255 
(preservatives  for,  257 
rules  to  be  observed  in  the  prep- 
aration of,  256 
strong  adhesive,  262 
sugar  and  lime,  265 
that  will  not  "sour,  262 
Venetian,  262 
Paste-board,  paste  for  joining  leather 

to,  267,  268 
Pastes  and  mucilages,  255-271 

for    special    purposes, 

261-271 

mucilages  and  cements,  prepara- 
tion of,  224-271 
Patent  glue,  150 
Patriarch  isinglass,  197 
Permanent  white,  addition  of,  to  glue, 

149 
Petroleum,  cement  to   withstand   the 

action  of,  231 
lamps,  cement  for,  231 
Phosphates,  extraction  of,  from  bones, 

115 
Phosphorus,    crude,    composition    of, 

131,  132 
distillation  of,   133- 

135 

purification  of,  132 
distillation  of,  127-132 
galley  furnace  for  distilling,  128, 

129 

loss  of,  132 
manufacture  of,  117-140 

of,    with    the    assistance    of 

electricity,  138-140 
operations  in  the  preparation  of,  117 
refined,  moulding  of,  135-137 
refining  and  purifying  of,  132-135 
receivers  for,  129 
removal  of,  from  the  receivers,  131 
residue  in  the  manufacture  of,  127 
sticks,  mode  of  forming,  135-137 
storing  of,  138 
Photographers,  caseine  mucilage   for 

266 

Photographic    printing,    gelatine    for 
183,  184 


INDEX. 


281 


Photo-lithography,  use  of  glue  in,  14 

Pierres  de  mastic,  226,  227 

Pipes  exposed  to  a  red  heat,  cement 

for  tightening  joints  of,  241 
Plaster  of  Paris,  244 

cement,  universal,  245 
statues,  cement  for,  244, 

245 

Pliable  paste,  263 
Porcelain,   cement  for,  231,  239,  240, 

241,  243,   245 
oil  cement  for,  229 
paste  for  attaching  labels  to,  270 
sulphur  cement  for,  232,  233 
Postage  stamps,  mucilage  for,  264 
Potassium  carbonate,  behavior  of  glue 

solution  towards,  7 

Printing  rollers,  compositions  for,  157 
Putty,  224,  225 


Q 


UICK  lime,  243 


RABBIT  skins,  18,  31 
Rag-engine,  39 

Raw  materials  and  their  preparation 
for  the  manufacture  of  glue, 
16-38 

collection  and  buying  of,  16 
division  of,  16 
Receivers   for   collecting    phosphorus, 

129 
removal  of  phosphorus  from  the, 

131 

Red  lead  cement,  225 
Resinous  cements,  220,  221,  229-233 
Retort-furnace,   Belgian,   for   the  car- 
bonization of  bones,  109-112 
Retorts,  127,  128 

Rochelle  salts,  behavior  of  glue  solu- 
tion towards,  7 
Rubber  and  gutta-percha  cements,  222. 

233-237 
cement  for,  250 

chemical  apparatus,  248, 

249 

glue  as  a  partial  substitute  for,  14 
Russia,  preparation  of  isinglass  in,  197, 

198 

Russian  glue,  149,  150 
isinglass,  197,  198 
steam  glue,  152 

SAHLSTROM'S  process  for  preparing 
a  substitute  for  isinglass,  gelatine 
and  glue,  203,  204 

Sal  ammoniac,  effect  of,  on  glue  solu- 
tion, 7 


Saltpetre,  effect  of,  on  glue  solution,  7 
Salts,  behavior   of  glue    solution    to- 
wards, 7,  8 

Samovey  leaf  isinglass,  197 
Sandpaper,  use   of  glue  in  the  manu- 
facture of,  12 
Sausage    skins,   glue    for    parchment 

paper  in  making,  154,  155 
Scheibler's  cement  for  chemical  appara- 
tus, 249 
Schneible,  J..  machine  for  cutting  the 

jelly  into  cakes  invented  by,  60-62 
Scrap-books,  paste  for,  266,  267 
Selenite,  244 
Seltsam's     apparatus     for    extracting 

bones,  84-86 
for    extracting    bones 
improved     by     Th. 
Richter.  88-90 
Serbat's  mastic,  227,  228 
Seubert's  apparatus  for  moulding  phos- 
phorus, 135,  136 
Sheds  for  glue-stock,  26 
Sheep  leather,  31 

skin  waste,  18 
Shell  lime.  28 

Shoemakers'  paste,  258,  259 
Siberian  purse  isinglass,  197 
Sieve  for  sorting  crushed  bones,  36,  37 
Silicate  of  soda,  240 
Silk,  artificial,  from  gelatine,  195 
Sinews,  1 
Size,  157-160 
glue,  150 

Sizing,  glue  in,  12 
Skin  gelatine,  166-170 

modern  process  of  preparing, 

167-170 
glue,    classification   of  operations 

in  the  manufacture  of,  43 
manufacture  of,  43-73 
-like  raw  materials,  16 
Skins,  paste  for,  267 
steeping  of,  18 

used  for  packing,  use  of,  for  glue,  19 
Sodium    carbonate,  behavior   of  glue 

solution  towards,  7 
Soft  putty,  225 

rubber  cement,  233,  234 
Sounds,  41 

Spiral  evaporators,  100,  101 
Stamping  mill  for  crushing  bones,  34, 

35 

Staple  isinglass,  197 
Starch  and  glue  cements,  222,  223 

paste,  255,  256,  261 
Steam,  apparatus  for  boiling  glue  with 
47-49 


282 


INDEX. 


Steam  boiler  cement,  250 
glue,  152 
high-pressure,  treatment  of  bones 

with,  105-107 
pipes,  cement  for,  250,  251 

oil  cement  free  from  lead  for, 

228 

cements  for,  228 
Steaming  bones,  75,  76 
Stephenson's  oil  cement,  228 
Stick  mastic  cement,  232 
Stone  lime,  28 

Stove  plates,  cracked,  cement  for,  246 
Stoves,  black  cement  for,  246 
Straiena,  252 

Straw,  use  of,  as  a  filter,  44 
Sugar  and  lime  paste,  265 
Sulphate  of  alumina,  use  of,  for  clari- 
fying glue  liquor,  54 
baryta,     addition     of,    to 

glue,  149 
Sulphuric  acid,  decomposition  of  bone 

ash  by,  119-125 
Sulphurous    acid,    absorption    of,    by 

bones,  92 
bleaching    glue    with, 

143-145 
glue-stock  with,  55, 

56 
dilute,     treatment     of 

bones  with,  38 
generation  of,  93,  94 
process  for  extracting 

bones,  92-94 
solution,  apparatus  for 
the     production    of, 
143,  144 
Surrons,  31 

Swinborne's  improved  patented  pro- 
cess for  the  preparation  of  gelatine, 
167 

fTlABLE    tops,    paste    for    attaching 
JL     cloth  or  leather  to,  269 
Tannery  waste,  yield  of  glue  from,  18 
Tannin  as  a  test  for  the  presence  of 

gelatine,  165 

effect  of,  on  glue  solution,  8 
removal   of,  from    leather  waste, 

39-41 
Tendons,  1 
Terne's  apparatus  for  the  generation  of 

sulphurous  acid,  94 
glue  boiler,  51,  52 

Terra- cotta  articles,  cement  for,  232 
Testing  glue  and  gelatine,  205-217 
Tin  foil,  paste  for  fastening  paper  on, 
266,  270 


Tin  paste  for  attaching  labels  to,  268 
Tires,  cement  for,  250 
Tools  for  cutting  the  jelly  into  cakes,  59 
Tortoise  shell,  cement  for,  232 

glue  imitations  of,  15 
Toys   indestructible  mass  for,  155 
Tragacanth,  261 

mucilage,  264 

Transition  stages  of  glue,  2,  3 
Tub-size,  manufacture  of,  158,  159 
Tungstic  glue,  155 
Turners,  cement  for,  229,  230 
Twine  netting,  objections  to,  66,  67 

UNDER  skin,  17 
Uses  of  glue,  10-15 

T7ACUUM  pans,  101-103 
V      Vasa  lymphatica,  1 
Vats,  clarifying,  53 
Veneers,  gelatine,  15,  186-193 
Venetian  paste,  262 

WALLS,  damp,  marine  glue  for,  235 
Wash   basins,  cement  for,  225, 

226 

Washing  drum,  22 
Waste,  green,  liming  of,  26,  27 
liming  of,  20 
putrefaction  of,  20,  21 
Water-glass  and  water  glass  cements, 

240-242 

constitution  of,  240 
Water-proof  cement,  227 

glue,  160 
proofing  fabrics,  161-163 

wrapping  paper,  160,  161 
tanks,  iron,  cement  for,  246 
Weavers'  looms,  worn-out  hinges  from, 

30 
Weidenbusch's  method  of  testing  glue, 

211-213 

Whalebone,  cement  for,  232 
Whale  glue,  204 
Whip  leather,  30 

White-lead,  addition  of,  to  glue,  149 
Wood,  cement  for,  230,  239,  240 

attaching       metal 
letters  to,  249 
to  metal,  251 
Wooden  vessels,  insoluble  cement  for, 

233 
Wrapping  paper,  water-proof,  160,  161 


Z 


INC  plates,  gelatinizing  liquors  upon, 

58,  59 
white  cement,  226 

addition  of,  to  glue,  149 


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